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Should the Volt Have a Free-Wheel Glide Pedal Position?

May 8th, 2008 | Posted in: Efficiency, Engineering

The following is a guest post by one of our regular readers, George K:

Lyle, you just had a great topic on features we’d like to see in Volt II. I’d like to share with you my #1 feature request for Volt I… “Pulse and Glide”.

Using it, you will get better mileage, and it’s fun to do.

Not sure how the Volt will work, but hybrids like the Prius and Insight provide for “PnG” very well. The reason is, their computer recognizes 3 positions for the “gas” pedal… accelerate, free-wheel glide, and decelerate (which should trickle charge the battery, but that’s another topic). So, between the accelerate and decelerate pedal position, you have that free-wheel glide sweet spot, where, for example on a slight down hill, the car will glide and never slow down.

“PnG” is a big deal among the Prius community. In fact, in Japan, there is a group called, “nenpimania”, Japanese for “mileage maniacs”, who drive around w/o a right shoe for better “PnG” foot feel!

So, lets try a “PnG” drive with the Volt! Lets say you are driving around with traffic flowing at 35 mph. You slowly push on the pedal (pulse), until you are doing 37 mph. Now, you release your pedal pressure slightly, until you are just about to begin a decel. Your energy screen confirms that, indeed, you are using no energy at all. You are now “gliding”! This glide feels great…like being in a sailboat! Without moving your foot, you ride this down to, say, 33 mph. and repeat. By the way, the more aerodynamic the car, the better “PnG” works.

In fact, using “PnG”, and playing the terrain, I was a winner of the ’06 HybridFest 20 mile open road rally (along with 2 other Priuses) averaging over 99.9 miles per gallon!

This is my #1 feature, not just because of the increased mileage, but also because it adds a fun challenge every time I drive the car. Driving electric is a real high, and adding “PnG”, that high will never go away!

[Per George's request, I asked GM about this option and was told by spokesman David Darovitz it could not be answered "for competitive reasons."]

Posted by: Lyle

112 Responses to “Should the Volt Have a Free-Wheel Glide Pedal Position?”

Greg Says:
May 8th, 2008 at 8:10 am

This sounds similar to what Saab had back in the 60’s. It was called a free-wheeling device. It would make it so that even when you would let off the accelerator the engine would not slow the car down. It was discontinued due to what some saw as a safety concern. I drove one and it was great and really improved mileage.

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Pat Says:
May 8th, 2008 at 8:24 am

Just think of all the gas you are making other people waste when you are doing this constant speed up slow down. Gas cars don’t like that.

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Joshua Bretz Says:
May 8th, 2008 at 8:25 am

1) Zero accelerator pedal (after positive accelerator) should be glide mode.

2) Zero accelerator pedal (after tapping the break pedal) should switch to constant speed mode, where regen keeps constant speed down a grade.

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Tim Says:
May 8th, 2008 at 8:34 am

Driving a car without the ability to coast when the accelerator pedal in a neutral position would be a VERY jerky proposition of acceleration/deceleration. GM has lots of experience with electric cars and they know that they would NOT be able to sell such a vehicle. I’m sure that they are already building the correct functionality into the software.

Some drivers MAY decide to play the “free wheel drive pulse hypermiling” game while ignoring all the other drivers on the road who are trying to drive normal and use their cruise control. These self-centered hypermilers are either oblivious to other drivers or they simply don’t care whether they cause an accident or not as long as they save a few pennies on gas. Unfortunately following the Golden Rule and common courtesy are becoming less commonplace each year.

Hypermilers are a driving hazard! Get with the rest of the traffic or get off the road!

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p2 Says:
May 8th, 2008 at 8:38 am

Ugh! Think how awful traffic would be with all of this surge and slow down. I want to be energy independant not force a heart attack stomping on the break when someone in front of me wants to gluide when I need to pulse. It sounds dangerous.

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Estero Says:
May 8th, 2008 at 8:42 am

It sounds good but I’m a little confused by the description provided by George K when he said:

“So, lets try a “PnG” drive with the Volt! Lets say you are driving around with traffic flowing at 35 mph. You slowly push on the pedal (pulse), until you are doing 37 mph. Now, you release your pedal pressure slightly, until you are just about to begin a decel. Your energy screen confirms that, indeed, you are using no energy at all. You are now “gliding”! This glide feels great…like being in a sailboat! Without moving your foot, you ride this down to, say, 33 mph. and repeat. By the way, the more aerodynamic the car, the better “PnG” works.”

Riding down from i.e. 37 to 33 suggests the pedal is in “decelerate” position rather than in “glide position”.

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ThombDbhomb Says:
May 8th, 2008 at 8:43 am

Without a free-wheel glide, you could only accelerate or decelerate. That won’t work. Of course there will be a free-wheel glide.

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Estero Says:
May 8th, 2008 at 8:46 am

On 2nd thought, I have to agree with #4 p2. The continual acceleration, gliding & deceleration could cause real problems. It is far better for one to stay with the flow of traffic rather than constantly changing speeds.

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Rashiid Amul Says:
May 8th, 2008 at 8:50 am

I give George K credit for achieving 99.9 mpg.
This PnG would require way more patience than I can muster myself.
My lead foot is way too heavy to come close to that.

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Evan Says:
May 8th, 2008 at 9:00 am

I like the free-wheel design that was implemented in the RAV4-EV. There’s a built in passive regeneration in normal use…you take your foot off the accelerator and the car will induce a mild regenerative drag that simulates a conventional car’s drag when you take your foot off the gas.

But there’s a button on the shifter that you can press that will release the drag and allow a free-wheel condition. I like the idea of being able to learn to manually select such a feature. That way serious ‘hypermilers’ can choose to use it, but ‘normal’ drivers will experience a more familiar feel when driving.

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Biodieseljeep Says:
May 8th, 2008 at 9:02 am

Many automatic cars have a “foot-off the gas” glide (eg my diesel Liberty). For those who drive a standard, this is called “nuetral”. Of course, Nuetral is not the same, as the engine is on and burning fuel. Anyways, I can’t see the big deal. Of course they will have something like the glide setting.

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Abattoir Says:
May 8th, 2008 at 9:11 am

It would be far more fuel-efficient to keep as close to a constant speed as possible. Accurate, computer-controlled cruise control is a far better option. If ‘PnG’ actually works on the Prius, it is due to some characteristic of how the Prius works, and would likely not work in the Volt.

It reminds me of people who think it’s cheaper to keep their A/C on at home all day, rather than only turning it on when they come home.

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Van Says:
May 8th, 2008 at 9:12 am

I think most of time the ICE will not be running, so the “gas pedal” position that simply maintains speed will use whatever energy is required given the vehicle mass, rolling resistance, drag.

PnG seems simply to lower average speed and train the drive to use a very light foot. Duh. The energy use meter will help us all become better, more fuel efficient drivers. (Not to mention $4.00+ gas.)

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frankyB Says:
May 8th, 2008 at 9:22 am

For me, such feature only make sence when you are cruising on long distance, isn’t that what cruise control is for? Just inplement this a cruise control feature that I can switch on and off.

Since this a serie Hybrid, the gaz saving won’t be much on short commute driving and I actually prefer to generate energy from braking in city traffic.

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Pat Says:
May 8th, 2008 at 9:28 am

I don’t understand this concept of pulse and glide. Say, I were driving a car propelled purely by an electric motor. Would it not be more efficient to supply only enough power to maintain speed instead of continually accelerating and decelerating?

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Luke Says:
May 8th, 2008 at 9:33 am

I’m not a fan of pulse and glide for real-world driving… For contents, fine, but in any kind of traffic, safety concerns take the the left-seat.

However, I’ve been driving my girlfriend’s Prius for the last week (long story), and the way the Prius slows down when you let your foot off the accelerator is kind-of annoying (I can even hear the PWM controller in some cases). I’d like to have a switch under the dashboard (right next to the place where she won’t let me install the stealth-switch) to be able to toggle the foot-off-gas behavior.

Having the Prius behave like a normal car is quite useful in some cases, and it does remind me that the regenerative braking is there. But I want to be able to coast without doing anything special when it’s appropriate to the situation.

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Luke Says:
May 8th, 2008 at 9:34 am

s/contents/contests/

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matt986 Says:
May 8th, 2008 at 9:34 am

Doesn’t seem to me like that’s a ‘feature’. It’s just where you’re not putting in any energy or letting the engine/motor slow you down.

I can do that in my Honda Fit, and my Porsche Boxster. The ‘feature’ isn’t something put in the car. The ‘feature’ is my right foot.

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Jason M. Hendler Says:
May 8th, 2008 at 9:36 am

Sounds like it would just create a lot of wear and tear on the motor / drive train. If GM is good at anything, it is in driver satisfaction with the feel of the vehicle’s response. Just let them determine the best driver experience.

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Eco Says:
May 8th, 2008 at 9:39 am

The question was “Would it not be more efficient to supply only enough power to maintain speed instead of continually accelerating and decelerating?”

Yes, that’s why some IC vehicles have cylinder shut-off while cruising at highway speed. “overdrive” transmissions work somewhat the same way.

Not being a car person, this may be taken care of by an accelerator pedal that imparts different voltage at different speeds.

Two accelerators would be cool; one for normal, one for highway cruising.

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Theoldguy Says:
May 8th, 2008 at 9:43 am

I tried the “free wheeling” with my 07 Maxx… over inflated the tires, put the car into nuetral on the down hills.and areas where (traffic permitting) coasted to just below the speed limit and gradually picking up speed….. shut the car off at the traffic lights that are more than a minute in duration.. and drove with a more moderate foot on the gas… I went from 9.1 L/100 KMS (31.04 MPG) to 8.7 L/100 KMS (32.46 MPG). So there is a savings involved but it entails a whole new type of driving methods. That’s a combined city/highway driving and not bad for a 3.5 V6. (in Canadian Gallons)

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TOM M Says:
May 8th, 2008 at 9:46 am

I’m telling my age on this one !

In 1953 and 1955 I owned Ford Crown Vickies that had standard transmissions that were equipped with a manual pull out overdrive.
This system were widely used in the fifties and was free wheeling.
To my recollection they were outlawed because of safety factors.
But they sure were fun to drive, you could stay in second gear all the way to a hundered. Driven respectfully , milage was great, but with gas at .27cents who was thinkng of milage.
I think free wheeling might be an issue with some state laws.
Tom

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szyszek Says:
May 8th, 2008 at 9:53 am

YES YES YES YES I want this feature! Seems that a lot of people are confusing it with cruise control. This has nothing to do with cruise control. I drive a stick shift and I use it all the time – I just put the car in neutral when I see a red light ahead or going downhill. It would be similar to putting an automatic car in neutral while driving. You just coast to a stop. A button on the shifter would be perfect. I am not sure if I would use it to “pulse and glide” as this is extremely annoing to other drivers, but I would definitely use it to coast the same way as I use it now with my stick shift Suzuki Grand Vitara. My truck is rated at 19/22 mpg (old way of calculating fuel economy, before EPA lowered it), I constantly get 23-24 mpg in mixed driving.

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mien green Says:
May 8th, 2008 at 10:07 am

http://www.autobloggreen.com/2008/05/07/are-hyper-milers-a-menace-on-the-road/

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Dave G Says:
May 8th, 2008 at 10:15 am

If people have fun competing to see how much gas mileage they can get with a Prius, that’s great. More power to them. But the Chevy Volt aspires to not use any gas at all, so I’m not sure how you would measure a winner in such a race. Also, once people convert to cheap electricity, conserving won’t be as much of an issue.

In addition, I don’t think the typical soccer mom is going to be interested in PnG. Let’s stay focused on mass market features and issues for the Volt and other F-flex cars. For example, CNN just did a piece about a boy on a bike that was hit by a Prius because he couldn’t hear it coming. They also interviewed blind people who are complaining about the lack of noise when the Prius is running with the ICE off. I happen to think most people can hear tires on asphalt, but I wonder how this will play out in the press…

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Canuck Says:
May 8th, 2008 at 10:26 am

Here is the proper explanation, albeit not from an expert. Feel free to correct.

The classical ICE either provides propulsion force (when fuel and air are supplied) or drag (when fuel and air intake are reduced to minimum, maybe none at all, not sure). There is now “free-wheel glide”. Only when transmission mechnically disconnects engine from wheels *THEN* you enter a “free-wheel glide” since wheels are now free, not connected to engine. So most manual trans. drivers like myself use this free-wheel mode simply by shifting into neutral. Most drivers with AT just don’t bother.

Of course, shifting to neutral and back into gear all the time would ruin transmission rather quickly. Therefore, we don’t glide often. I may do it up to 1km before a red light as I know that I’ll have to stop. That is a typical free-wheel glide example for MT drivers. In order to maintain a certain speed MT driver would have to shift very often, so it is not done.

All that concernes “typical” ICE. The drag is achieved by engine during compressions cycles when car’s kinetic energy is used to compress cylinder contents. Usually it is air/fuel mixture. However when slowing down then cylinder is empty so compression is a wasted energy and car slows down as its kinetic energy is drained. This happens when you take your foot off the accelerator pedal.

Some newer engines (not sure about Prius, but likely its engine has this feature) actually can open and leave open cylinder valves thus avoiding compression cycle. As cylinder is not closed the compression doesn’t take place. It is almost energy neutral (nothing lost or gained). This mode is used for “glide” effect. Motor still turns but offers minimal drag – glide. I am guessing this takes place when Prius is half way between accelerate and slow down pedal positions.

The adcantage here is that transmission is not used as motor still turns. Of course, Prius doesn’t have a classical transmission so …. Anyway motor is still in motion, just offers minimal drag. Still, air resistance and road friction slow down a car, albeit much more gradually.

Prius has a choice of using electric motor or ICE. So during the “pulse” phase depending on speed and other parameters Prius will use one of the motors to restore lost speed. If pulse/glide is done often then speed loss could be minimal. Therefore it doesn’t need to be dangerous. In fact, if car computer itself controlled pulse/glide mode then you could maintain a fairly constant speed without the hassle of controlling accelerator. I expect this feature to show up in Volt and future Prius models.

In fact, pulse/glide mode is even easier to implement in Volt. There are not cylinders, no compression cycles, etc. In fact, it would be a simple feature of cruise control. You set desired speed and Volt engine supplies only enough current to maintain the speed. Come to think of it, there is no need for glide at all. It is a simple minimim power input for speed maintenance.

So to recap,
Pulse/glide is an optimum energy use tehcnique for car designs that still use ICE as a primary propulsion. Car computer could implement pulse/guide to maintain a safe steady speed. Primary electric propulsion cars like Volt don’t need such a mode because electric motor doesn’t inherently provide drag unless it is turned into a generator. Electric motor always uses exactly the amount of current needed to accelerate or maintain desired speed.

The only thing I am not sure about is how is electric motor turned into generator and how much drag does is provide when no current is supplied.

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szyszek Says:
May 8th, 2008 at 10:27 am

Dave G – “But the Chevy Volt aspires to not use any gas at all, so I’m not sure how you would measure a winner in such a race” – very easy: Volt’s range before ICE kicks in! My roundtrip to work is about 40 miles. I would like to use coasting as means to extend electric only range so ICE does not start.
Soccer moms will not buy the early Volts. Car enthusiasts like you and me will buy one, people that understand the technology behind it. Many of us will use that little button for coasting. It cost next to nothing to install it in the Volt. People that do not want to use it can just ignore it.

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Dave B Says:
May 8th, 2008 at 10:30 am

If this PnG feature adds cost and/or delays the production, I’m really not interested. Plus I agree with the other posts that are of the mentality that I’d the target of road rage (rightly so) for speeding up and slowing down constantly for those behind me.

Let’s get the BEV show on the road already.

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Statik Says:
May 8th, 2008 at 10:30 am

I think some things can be taken too far. This might be one of those times.

I have been guilty of being a hypermiler. Never got to the fabled 100MPG….best I could do was 92. After doing it a couple times, I realized I was trading a few MPGs for being a jackass on the road.

I have since return to being a normal human on the road and at the pump. MPG solutions have to still be mindful of respecting the driving standards of the mass population.

This is one of the reasons I disprize low speed EVs, nothing more frustrating that getting stuck behind one of these contraptions in the city….or turtle accelerators. IMO, there should be a minimum performance standard (that makes sense) to put a car on any gov’t assumed road.

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George K Says:
May 8th, 2008 at 10:34 am

#4 p2
I should have included the standard PnG disclaimer… don’t do it when it’s not appropriate! Courtesy on the road is always a concern. When I do it, no one around me even knows it’s happening. I might use it for 2 or 3 PnG’s. Then a car starts getting closer and I go back to steady driving (and lower mileage).

It’s a fun added dimension to the driving experience, and a way to watch your mileage increase from drive to drive.

By the way, on the Prius, the glide spot is so small that most people don’t know it’s there. When I first read about it, I couldn’t find it. It takes a little practice.

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N Riley Says:
May 8th, 2008 at 10:34 am

I don’t know about you all, but when i drive in traffic I am constantly speeding up and slowing down because of normal traffic conditions. Mostly normal traffic conditions are defined as some butt-hole driving 25 in a 45 mph zone in one lane and drivers coming up on him/her and switching over to your lane. Usually the switching of lanes causes drivers in the new lane to slow up to let the driver in and to get back up to speed.

Just normal driving can be hairy enough. I don’t know enough about the PnG feature to make a decision, but I would hope GM will take a look at it and offer it if it makes sense. I like the idea of a button on the shifter or steering wheel that engages/disengages the feature. But make the “feature” an option that the owner has to pay for and not part of the base price of the car. Most of us would probably pass on many cost features unless we feel strongly about it.

Speaking of features and their cost. I know that we have discussed the cost of a Prius vs a Volt. It is next to impossible to find a Prius without additional cost packages being already added that raises the average cost of a Prius from around $22,000 to about $27,000. What I would like GM to do is keep the Volt as free from the unnecessary items in the packages as possible. I don’t know how to do that, but it sure would be good if it could be done.

If someone wants a feature not offered in the package, let them pay for it. To me the car should come as a base price and dealers should always keep a small number of them in stock. I don’t know. What does everyone else think?

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TOM M Says:
May 8th, 2008 at 10:38 am

#24 Dave G
I sure agree with you with the exception that we as drivers need to be responsible drivers. I am not blind or physically disabled but crossing the street is a major concern when walking. Todays drivers have no respect for the pedestrians and you take your life in your hands when you step off the curb. Doesn’t matter if you are in the crosswalk or not !
Lets all go back to being courteous and responsible drivers !!!

Tom

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Joe Says:
May 8th, 2008 at 10:44 am

I do a lot of that gliding with my new Corvette and I can get about 32.5 mpg on the highway. At any rate, I have faith that GM is fully aware of all these features and I trust that if any of them are good, they will use that technology.

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szyszek Says:
May 8th, 2008 at 10:46 am

To everyone that is concerned about cost and/or increased complexity of the Volt when this feature is added: no need to worry. We are talking about a switch that turns off regenerative braking when you take your foot off the accelerator. When you take your foot off the accelerator, even though you do not touch the brake pedal, the car will turn the motor into a generator to take advantage of the speed – the car assumes that since you took your foot off the accelerator, you want to slow down. All we want is to turn it off. That’s all. $0.50 switch and some wires.

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N Riley Says:
May 8th, 2008 at 10:47 am

After reading more of the post since I started my comments earlier, I now believe this PnG feature would not be needed on the Volt. For the first 40 or so miles it will operate on EV mode. PnG would not apply in that case, I would think.

So, I say, GM forget that feature and get busy building a base Volt with just enough features to make us happy. Offer it at the $30,000 price and do it as soon as possible. Worry about adding other features with version 2.

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Chris Says:
May 8th, 2008 at 10:49 am

@ szyszek – so how would charging the battery as it rolls downhill not extend the range of the all electric driving? If the battery is being charged (through regen), it stands to reason that it would be able to operate electric-only for a longer period of time, right? Not charging it, by coasting, would accomplish basically the same thing, but recharging could allow for a longer extension than not coasting.

Since we haven’t test driven a Volt yet, it could all be a wash either way, but personally, I’d prefer to have my batteries getting recharged while I “coast” downhill.

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szyszek Says:
May 8th, 2008 at 10:51 am

N Riley – sorry, but you are incorrect – PnG would apply in electric only mode and extend the Volt’s range. Like I said in my previous post – it is just a switch. You do not need to use it if you don’t want it. Adding an on/off switch would not increase the price or complexity of the car.

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szyszek Says:
May 8th, 2008 at 10:56 am

Chris – here is why: If you do not coast, then you have to keep your foot on the accelerator longer as regen will slow your car quicker. Regen is only getting back part of the energy spent. When you coast, you do not use any energy or recapture the same energy, therefore your range is extended. To the car it is the same as being parked in your driveway, but miles are pilling on

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noel park Says:
May 8th, 2008 at 11:02 am

#9 Evan, #15 Luke, #22 & #26 szyszek:

I agree. I would strongly encourage a button to allow me do disengage the regenerative braking and coast when I prefer to do so.

I have been an advocate for making a lot of bells and whistles optional to try to keep the base price of the car down. As with many others, I do not care to pay for features I do not need. In this case, as someone said, the cost should be pretty minimal, so why not just go ahead and do it. Also, my wife is starting to make noises about top of the line interiors, navigation systems, and “no more stripper cars”, so maybe I am going to have to eat my words anyway!

#30 N Riley:

In SoCal there are plenty of Priuses available with the first option package at about 23K. There are NONE at the base price. But when someone wants the nav system (no prize for guessing who), it’s an instant 27K package.

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Joe Says:
May 8th, 2008 at 11:02 am

To me using the brake to initiate gliding is not the way to go. The best way is to use an electronic load control. The load control would always monitor the load on the electric motor. If the load control senses no load, then it would put the four wheels in glide mode. Should you have to put your brakes on while in glide mode, then the load control would sense that and it would put the regenerative braking system on.

I know the Volt will have a load control and it l will be used as a multipurpose instrument.

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N Riley Says:
May 8th, 2008 at 11:03 am

szyszek

GM certainly needs to review this. I will agree with you and others that further study should be in the best interest of all concerned.

Thanks for all the info on PnG. It is something I know absolutely nothing about. My Grandpa used to say when you know nothing about something it is best to just sit and listen. Afterwards you will at least know something.

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Mark Says:
May 8th, 2008 at 11:09 am

Hey, if this doesn’t increase the cost of the car by too much…

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RB Says:
May 8th, 2008 at 11:10 am

I love this idea. When one lives in an area that’s mostly hills, such as my area, there is no such thing as steady pedal pressure resulting in uniform speed. Under many circumstances it would be great to be able simply to roll forward, as if the car was in neutral, without having to shift to neutral. It can be achieved simply by having, in effect, three positions on the accelerator pedal (1) pedal down, accelerate (2) middle, glide (3) pedal up, slowing due to regenerative braking. Of course, one sometimes has to put on the brakes, but that’s a different matter.

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szyszek Says:
May 8th, 2008 at 11:14 am

Here are the instructions on how to PnG in Toyota Prius: http://www.ehow.com/how_2093197_pulse-glide-toyota-prius.html. Notice #3, it says that Prius will turn itself into a generator when you take your foot of the accelerator. Point #4 is what we are talking about here – it seems that if you press the accelerator slightly, there will be a position where the car is not using any energy and not trying to recapture any energy. The same can be accomplished with a simple switch.

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N Riley Says:
May 8th, 2008 at 11:16 am

noel park

After shopping for a Prius on-line with local dealers, the average price seems to be around $27,000. One dealer shows a Prius for $24,000 while the others listed range from $27,000 to almost $30,000. Each dealer will show one or two Priuses as “in stock” and the other five or so will be shown as “available”. Meaning the available ones can be brought in from a dealer within a one state area.

Our local Toyota dealers are package crazy. Or they just know the buying public better than I do. Certainly not hard to do. I guess we all want more car than we want to pay for. But I wish there were more lower cost packages than what is offered. They jump in price pretty quickly from package 1 to 2 to 3, etc. I suppose all autos are sold like that (with costly packages added).

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jabroni Says:
May 8th, 2008 at 11:17 am

I never understood pulse and glide. Have you ever tried it? Talk about taking the joy out of driving, it is like a full time job on top the driving task….what a pain in as*

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N Riley Says:
May 8th, 2008 at 11:20 am

Using the gas pedal to cause PnG seems “tricky” to me. If we have a switch to turn it on/off, it seems the computer could control when PnG is engaged or in effect, whatever you want to call it.

Most of us will have a hard time finding the positions using the pedal. Maybe I am wrong, but I don’t think so. You all know that I have never been wrong on any of these post, don’t you?

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Terry Says:
May 8th, 2008 at 11:27 am

Excuse me, I thought this was a Volt forum, not a Prius forum.

Volt owners will not have to PnG, draft large trucks, or any of the other insane things hypermiling Prius owners do to get a few more miles a gallon. Some of the things hypermilers do to get their higher miles per gallon are truly dangerous. If you drive your Volt 40 miles or less, you use NO GAS – ever.

This is not to put down Prius owners. They bought an early version of the Volt, called the Prius, made by Toyota. We don’t have the Volt yet. But when we do, the unlimited MPG is going to be so sweet.

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Mike756 Says:
May 8th, 2008 at 11:28 am

Push the accelerator=accelerate
Ease off accelerator=”free wheel glide” to new slower speed
Foot off the accelerator=”free wheel glide”
Brake=slow down using dynamic braking

In other words, make it work just like a regular car.

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dodahman Says:
May 8th, 2008 at 11:43 am

That’s cool with me, as long as I can do big smoky burnouts from stoplights and waste Mustangs without using any gas.

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greg woulf Says:
May 8th, 2008 at 11:56 am

I’m not against having glide, but only if it’s transparent.

I feel that this car is special for what it can do, but I think it’s earth changing in how I think it will make people come to accept EV’s, or EV’s with assist.

The way that happens is to make it meet every standard applied to an ICE of the same size. If the driver has to do anything more than they do now in their ICE it’s harmful to that goal. Plugging a car in at night is an inconvenience. If you had to plug it in and go to the gas station both, then It would be less convenient. The Volt will cost you a tiny bit of time every night plugging it in at home, but will save that time back easily in saved trips to the gas station.

If they force someone to check gauges and options before they drive, then people aren’t going to want to deal with it. I know engineers who don’t want to deal with it, so I know this is true. Anything that’s less than an ICE will be magnified.

So, as an option, I’m all for it, if it’s invisible to all the people that never want to know it’s an option.

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Rashiid Amul Says:
May 8th, 2008 at 11:58 am

PnG sounds too much like micromanaging. I like to hit the gas, dump the clutch, and I’m off to wherever. Most of the time, people are in my way. In Connecticut, where I live, the law on the highway is to stay right except to pass. Stupid people ignore this law and stay in the left lane bottlenecking traffic by going slow. I thank George K for doing PnG only when it is safe and other drivers aren’t around. But PnG won’t be for me.

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Neil Says:
May 8th, 2008 at 11:59 am

When you’re comparing the Volt to the Prius, you’re comparing a series hybrid (or E-REV if you prefer) to a parallel hybrid. While a glide feature is useful for both, the Pulse is only truly useful on the parallel. If you pulse a parallel the ICE directly powers the wheels and therefore you don’t lose energy converting that power to electricity. Since all power in the Volt gets converted to electricity anyway, there isn’t much point in Pulsing.

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Rashiid Amul Says:
May 8th, 2008 at 12:13 pm

#50, greg woulf, I agree with almost everything you said.
I do however think the plugging my car in every night is not an inconvenience, but a HUGE time saver. I look forward to the day when I can spend 10-15 seconds plugging in my car. This small amount of time is immeasurable in my busy schedule.

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calgaryvolt Says:
May 8th, 2008 at 12:22 pm

#20 Oldguy,

I tend to use neutral for a lot of coasting as well in my normal ICE vehicle. I too shut down my vehicle at longer lights (anything more than one minute.) I will almost always pop my car into neutral to coast down a hill or up to a traffic light or whatever. This works exceptionally well when driving through the mountain passes between Alberta and BC because of all the long down hill stretches. I think that it might put a little more stress on the transmission and starter but I’m not to concerned seeing that my vehicle is covered under warranty and I will likely traded it, or use it very little, after 5 years of ownership.

I’m not a tree-hugging eco-activist but I can see the benefits to conserving resources and being easier on the environment. I think that an easy way to change fuel consumption and the demand for oil and gasoline is to slightly modify your driving habits. People need to try coasting more, shut off your vehicles at long lights or when your stuck in grid lock going no where fast. Get out of the car and go inside the restaraunt instead of using the drive-thru. Shut your car off when going into the bank or other places. Sometimes it really boggles my mind when I see so much waste.

I used to have a neighbour who owned two larger trucks (SUV’s.) I would hope into the shower in the morning and look out the bathroom window in the winter to see how looked outside to figure out what I wanted to wear and I would see one or both trucks warming up in the driveway. Thirty minutes later, or so, I would put out of the garage only to find that the trucks were still warming up. These were brand new trucks that didn’t require more than a minute to warm up (if any time at all.) The other neighbour next door would drive her car to the mailbox and back everyday. This was not one the way home or when leaving but this was a special trip. The walk to mailbox was two minutes at the most, return trip.

Driving behind someone that is doing some sort of pulse and glide technique would bother me greatly especially out on the open road. I use my cruise control all the time and I hate having to re-adjust and brake and such.

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ThombDbhomb Says:
May 8th, 2008 at 12:34 pm

Instead of PnG, I’d like the Volt to have a giant magnet that I can use like a “tractor beam.” I’d use my tractor beam on tractor/trailers going down the interstate, allowing the tractor/trailer to tow me.

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AES Says:
May 8th, 2008 at 12:34 pm

Free wheel glide?? How about just dipping in the clutch while driving a manual transmission? Prius owners are such dorks, thinking they’ve invented something new. And for the record, that car’s “MPG” screen is such a crock of crap – my old boss’s would just get stuck on 99.9 no matter what he was doing.

As for how it pertains to the Volt, the motor is going to be connected to the wheels full time, so it would be a matter of how you modify the throttle by wire and brake by wire controls. The accelerator pedal would apply neither energy nor regen braking when it wasn’t depressed.

This is about the opposite of the traditional EV setup where the throttle pedal controlled both acceleration and regen. In other words, if you were going a steady speed with the throttle pressed, and let up completely, the regen braking would come on full force.

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JimShelton Says:
May 8th, 2008 at 12:56 pm

48. Mike756

**Push the accelerator=accelerate
**Ease off accelerator=”free wheel glide” to new slower speed
**Foot off the accelerator=”free wheel glide”
**Brake=slow down using dynamic braking
**In other words, make it work just like a regular car.

Mike, That just the point. What you say above is not how a regular car operates. A regular car decelerates quickly due to transmission and mainly engine drag when your foot is off the accelerator. Next time your on the highway (With nobody behide you) do the following.

1) Get up to speed, then let off the gas pedal, and see how fast you slow down.

2) Get up to the same speed, The switch the transmission to Neutral(Automatic or Manual). I think you will see you will slow down at a slower rate.

I think having the car free-wheel with the foot off the accelerator would be disconcerting, but something somebody could get used to within a few days. But if you are switching between a regular ICE car and the VOLT. It could be dangerous if you forget what car you were in. I know an Apache Helicopter pilot that lost more altitude than he wanted because he went the wrong way with the collective(Throttle) after he spent a day in a V-22 Osprey simulator. (The V-22 no longer has a half collective/throttle control because of this problem, It is all throttle like a fighter plane)

My preference on this, is I would like to have it, just like it is on the Prius, but with maybe a bigger Free-wheeling sweet spot. The only time I would use it would be going down-hill. It would be natural on a hill to ease the accelerator until it was free-wheeling and maintaining speed. If it was a steep hill. I would continue to easy the pedal and it would start regenerative breaking. If it was really steep, I would hit the break to increase regenerative breaking to maintain a constant speed.

my two cents..

Jim

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szyszek Says:
May 8th, 2008 at 1:03 pm

JimShelton – Exactly. Perfect explanation. I would prefer a button however.

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Mike D Says:
May 8th, 2008 at 1:47 pm

Instead of PnG, wouldn’t it be better for the VOLT if it had a feature that kept it in charge mode while keeping deceleration at a minimum? Like braking very slightly, but enough to kick in brake regeneration mode. Anyone have thoughts on this?

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szyszek Says:
May 8th, 2008 at 1:52 pm

Mike D – Volt most likely will have this feature, what we are talking about here is an option to turn it off. That’s the point of the whole discussion.

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Jean-Charles Jacquemin Says:
May 8th, 2008 at 1:55 pm

Biodieseljeep #10,

You wrote :”Many automatic cars have a “foot-off the gas” glide (eg my diesel Liberty). For those who drive a standard, this is called “neutral”.”.

My experience since my previous Astra diesel and now with either my Corsa diesel or my “new” (2005) Astra diesel, I may experience this “foot-off the gas” sensation due the electronic regulation of the engine, this is very useful in the traffic jams, slow urban driving, difficult accesses with narrow ramps, etc. You may go up to 30 mph in fourth (manual) speed with your feet off pedals, …

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N Riley Says:
May 8th, 2008 at 2:22 pm

What I want to find out (Lyle?) is what the console and displays are going to look like and what are they going to tell us. I am sure GM can improve on the Prius here. I have looked at other hybrids and did not think their informational displays were as good as the Prius. The biggest draw back I see with the current Prius is it is not tilted towards the driver more to make it easier to see. I would like the informational display to be more in front of the driver if not where the current odometer, speedometer, etc are now.

You need to see your speed, mpg, consumption (maybe) and a few other things. Some things like vehicle temp, oil, etc could be displayed on other displays. I want as much information about the operational aspects of the Volt to be easily seen as possible on the “base” or default display. There needs to be a toggle up/down button on the steering wheel (like sound level for the radio) to let you toggle or scroll through the different informational displays. This would keep your hands on the steering wheel. Should be safer.

More ideas, please. Maybe GM has not thought of some of these and they might need our help in pointing out what they are missing.

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OhmExcited Says:
May 8th, 2008 at 2:33 pm

How did it work with the EV1? My guess is that the Volt implementation won’t be radically different.

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N Riley Says:
May 8th, 2008 at 2:34 pm

One other thing. The informational displays need to be color LCD, not monochrome as is the Prius or at least it appears to be.

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N Riley Says:
May 8th, 2008 at 3:00 pm

Speaking of the EV1, I went to the EV1 Club site and it is worth us Volt fans to take a look at.

http://ev1-club.power.net/

There are a lot of similar features between the Volt and the EV1.

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OhmExcited Says:
May 8th, 2008 at 3:48 pm

I found some good stuff on coast/regen from a wish list items at an EV1 club. It looks like the EV1 had a coast down buton. I wonder if that will be in the Volt. GM could probably find a lot of gems by reading this material here and elsewhere.

http://www.eanet.com/ev1-club/wishlist.htm

2. State of “re-gen” indicator.
————————–
It would be great to have an indication, on the display, of
“how much” energy is being put back into the batteries when
“coast down” is pressed or brakes applied (or both). We all
are trying to fine tune our driving habits and an indicator
like that can help tremendously. (many)
2a. In “power usage” mode have the bars come down from the TOP
to indicate regen. The bars all disappear (as at present)
when there is equilibrium, but then when there are 100 watts
of net regen, just the very top bar lights up, when there
are 500 watts, the top two bars light, 1000 watts, the top
three bars… and so on. No matter what, the bottom bar
should not light up so as not to confuse regen with power
usage. This feature require no modifications to the display
unit and resolution of the bars is maintained. (Tom Dowling)
………………………..

4. Power setting on the cruise control.
———————————–
4a. Cruise control is great. Especially with this responsive
car. When using the cruise control, I’m dismayed when the
“power used” goes over 50% – to keep up the speed over a
hill for example. It would be nice to have a “power saving
mode” for the cruise control, that when turned on, will
keep the speed as long as power used doesn’t go over ,
say, 55% . (Kodama, Avi Hershkovitz)
4b. Also, we’d like the coast down button to control whether
the cruise control allowed the car to coast & gain speed
going down-hill or to engage the re-gen and keep the speed
steady. thus on the hills you’d speed up going down and
coast up next. This is more efficient use of power and if
I’m driving for range I’ll use these tricks. (Chris Yoder)
4c. Buttons for speeds, i.e. 25m/h, 30m/h, 45m/h, 55m/h…
I don’t really car how fast I drive, so I just drive
exactly the legal limit using the auto-pilot. Only annoyance
is having to set it again after stopping briefly at a red
light. (Dirk Harms-Merbitz)
………………………..
11. Braking.
——-
An indicator showing when re-gen and friction braking is being used -
This would allow us to train ourselves to brake efficiently as well
as make it unnecessary to use the coast-down feature when it would be
safer to indicate to drivers behind the car that the car is slowing
down. (Kodama)
………………………..
12e. Move the “coast down” button to somewhere on the steering
wheel. This way one would not need to take ones hand off
the steering to change the re-gen mode. (Margaret Cheng)

………………………..

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Evan Says:
May 8th, 2008 at 4:04 pm

Guys,
The ability to free wheel will not provide the same Pulse & glide functionality as it would in a Prius. Indeed in most cases it will, indeed, make more sense to maintain a steady speed.

But there will be situations in your day to day driving that you’ll be able to extend the battery range and use less energy even in AEV mode. And remember, charging that battery isn’t free…so the less energy you use the better. Also, I foresee you guys posting “I made it 56 miles AEV!!” and stuff like that as you learn to hypermile your Volt.

So, the situations I foresee a free-wheel feature being useful….
Downhill. Remove your foot from the accelerator and hit the button…on an open road you’ll actually gain speed using zero battery. That extra speed means more momentum that will carry you some distance before you need to step on the accelerator again to maintain your target speed. Also, you’ll be able to get off the accelerator that much more quickly as you approach a stop…if there is built in regeneration you may only be able to coast 1/4th mile to a stop, in free wheel you may be able to glide a full 1/2 mile to the same light. All those little extra 1/4 miles start adding up…that’s what hypermiling is all about.

And for you guys that feel it’s too much trouble..fine, ignore the feature. I believe the EV1 had a freewheel feature, and as I pointed out up in post 10 the RAV4EV had it as a button on the shifter. When you’re trying to stretch that battery range little extras like that will mean a lot.

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Statik Says:
May 8th, 2008 at 4:13 pm

In other news:

Gm ponies up 200 million to end American Axle strike.

“…the strike cost GM’s North American division $800 million because the company lost production of about 100,000 vehicles”

“GM also said the strike has cut its liquidity by $2.1 billion but said it has the money to meet its needs even if U.S. industrywide auto sales continue to drop.”

Another 2.3 billion down the drain…19.9 left.

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szyszek Says:
May 8th, 2008 at 4:26 pm

OhmExcited – great find! If EV1 had the button, chances are good that the Volt will have one too.

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Nelson Says:
May 8th, 2008 at 4:56 pm

O.K. I confess I could be mistaken for a ‘hypermilers’. I always blamed it on good eyesight and a desire to extend the life of my brake pads. I typically drive on a 4 mile, 40 mph stretch where there are only two traffic lights. If I see a light go from green to yellow I take my foot off the accelerator and coast until the light turns green. Of course I move to the right lane and let those pressed for time rushed to the red light, only to have to break when they get there. I’m confident the folks at GM will implement a great driving feel with the Volt.

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Joe Says:
May 8th, 2008 at 5:29 pm

Folks I’ve said it before and I’ll say it again. With an electronic load control many many things can be done with an electric drive. For example, If the Volt is going downhill with the driver is not pressing down on the accelerator pedal, the load control would senses this and if programed correctly, it could give an electrical signal that would make the car glide. At the touch of the brake, it could activate the regen system to charge the battery. Being that a load control is a power monitoring device, it could also be used to monitor the charge and discharge rate of the battery. The two mode transmission uses this technology and I’m sure GM will use it in the Volt.

For those who who to know more about a simple load control, check this site below.

http://www.loadcontrols.com/whatisaloadcontrol/whatisaloadcontrol.html

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noel park Says:
May 8th, 2008 at 6:07 pm

This is not exactly new – plenty of people have said here before in one way or another – but here goes anyway.

These Volt details are fascinating. I get as involved in them as anyone sometimes. Even so, I think that the most effective thing we can do is not get too wrapped up in them to the detriment of the most important thing we can do – cheerlead to get the Volt into the showrooms.

Come on GM, get the !@#$%^ car into the showrooms! Time’s a wastin’. We’re on the waiting list. We’re ready to make deposits. We’ve got the money to buy the cars. Let’s get it done!

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noel park Says:
May 8th, 2008 at 6:10 pm

I could add:

Don’t you feel the hot breath of Toyota, BYD, et al, on the back of your necks? But I don’t want to detract from the core message.

Which is, as the man said, “Get ‘er done!”

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bruce g Says:
May 8th, 2008 at 6:19 pm

Nasaman,
Nice description, we are the Cheerleaders.
GM-Volt.com are an unusual mob,there would not have been many times in history that a mob cajoled or cheered to get a task done.
I can not think of a similar group cheering on hydrogen technology, its almost like batteries are the peoples choice.
I wonder what the automotive engineers think about batteries, a necessary nuisance? Far too much chemistry for their taste?
Ruins the look of the car?

The mob will probably get their way, they did in Paris.

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bruce g Says:
May 8th, 2008 at 6:34 pm

Sorry Noel, I was having a senior moment.

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GSP Says:
May 8th, 2008 at 6:43 pm

#53 Neil,

Your comment perfectly sumarizes the situation:

“When you’re comparing the Volt to the Prius, you’re comparing a series hybrid (or E-REV if you prefer) to a parallel hybrid. While a glide feature is useful for both, the Pulse is only truly useful on the parallel. If you pulse a parallel the ICE directly powers the wheels and therefore you don’t lose energy converting that power to electricity. Since all power in the Volt gets converted to electricity anyway, there isn’t much point in Pulsing.”

Pulse doesn’t help with an EV, but I definately want to easily “glide” (coast) with my Volt, to extend the EV range. I don’t think that a button is needed. Just set it up like #58 JimShelton suggested:

“My preference on this, is I would like to have it, just like it is on the Prius, but with maybe a bigger Free-wheeling sweet spot.”

This is my preference also, and I hope GM is listening.

GSP

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noel park Says:
May 8th, 2008 at 7:13 pm

#76 bruce g:

Join the club. Why should you be any different from the rest of us?
Pretty cool whan the “senior moment” crowd are cheerleading for this citting edge new technology, IMHO.

As to #75, thanks for your kind words. If I know engineers, and I think I do as I am one, I would make a large bet that they love the new battery technology. Rising to the challenge of solving problems and developing new ways of doing things, let alone contributing to resolving existential issues facing our country, are exactly the things they thrive on.

As p****d off as i get at GM for its corporate inertia, i have perfect confidence thatt they have the engineering and technical talent to achieve a truly world class result here. If management will give them proper leadership and resources, it is a done deal.

“Lead, follow, or get out of the way.”

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RB Says:
May 8th, 2008 at 7:46 pm

#69 Statik
I agree, even though I wish it was not so. Borrowing from a famous politician, “A billion here, a billion there, and pretty soon you are in real trouble.” Maybe GM can hold on long enough to get some cars that people actually want to buy out the door.

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Shawn Marshall Says:
May 8th, 2008 at 8:00 pm

This site is getting whacky with technocracky. Let’s just hope GM gives us a good car at an attractive price that will send a message to our cynical offshore exploiters in OPEC and elsewhere that their little game of twist the tail is finis. Maybe our country can recover a little initiative in a commercial venture rather than expending all our efforts on defense systems. If our economy fails, there is nothing else, and for many years the fundamentals of a sound USA economy have been ignored. What’s good for GM is good for us.

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Computer-codger Says:
May 8th, 2008 at 8:16 pm

I read this site every day but seldom write responses. But readers from months back will remember me. The way the Volt is driven is of special interest to me. I have thought about how one would drive the Volt quite a bit. So here goes once more.

The accelerator pedal is not the best devise to detect 3 states: accelerate, coast/glide, and decelerate. I agree with those of you that say setting the coast/glide state could be a little tricky to do. I can imagine driving the Volt almost exclusively with cruise control on, in the city or on the highway; that is, if cruise control is designed the way I hope it will be. Coasting/gliding could easily be incorporated with the same control switches as cruise control. Let me explain.

Here is the way I hope cruise control works. Cruise control should maintain the set speed within 1-2 mph up and down hills, including steep hills. There should be a switch to enable and disable cruise control; and, of course, tapping the brake pedal always disables cruise control. There should be a 4-way rocker switch on the steering wheel that can be thumb controlled. Switch position 2 is the normal switch setting if switch is not being depressed. Switch position 1 is while being pressed forward. Switch position 3 is while being pressed backward slightly. And switch position 4 is while being pressed all the way backward. Switch position 1, 3 and 4 are spring loaded so that if switch is not being depressed the switch always returns to position 2.
Interpretations of the 4 switch positions are:
1. Press forward means accelerate at a non-linear rate, but at a safe rate. If not in cruise control mode then enable cruise control mode. When switch is released remember current speed and go to normal switch setting, position 2.
2. Maintain current speed within 1-2 mph while in cruise control mode. If in cruise control mode and the accelerator pedal is pressed then accelerate until accelerator pedal is at steady state, and cruise control remembers current speed. If cruise control mode is off then the accelerator pedal controls the speed.
3. Press backward slightly means coast/glide, do not maintain speed and do not apply regenerative braking. If in cruise control mode when switch position 3 released, cruise control remembers current speed. If not in cruise control mode then coast until switch is released and go to switch position 2.
4. Press backward all the way means decelerate using regenerative braking, at a non-linear rate; that is, the longer position 4 is pressed the stronger the regenerative braking is applied. If in cruise control mode when switch position 4 is released cruise control will remember the current speed and go to normal switch setting, position 2. If not in cruise control mode then decelerate in the same way and go to switch position 2.

This method of speed control solves several problems. As stated earlier I can imagine driving in the city or highway almost always with cruise control on. I think you would soon learn how to drive with hands only and you apply the brake pedal with your foot only when needed. You could come down a steep incline and use decelerate switch position 4 to slow to the rate needed to safely control you speed without fear of brakes over heating.

Also a paraplegic person could drive the Volt with only the addition of a hand brake control.

I am aware that some people are left handed and there might be a question of whether the left or right thumb control would be an issue. I think a left-handed person would learn how to use a right thumb control just as they learn to use their right foot for accelerator and brake pedal control. The thumb control is essentially accelerator and brake control except in emergencies.

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Ian Ward Says:
May 8th, 2008 at 8:32 pm

My Ford Ranger EV has no coasting pedal position – you actually have to put the “gear” selector in neutral because they programmed the controller to simulate engine braking in both “D” (drive) and “E” (Economy) modes. Now, it’s not really a gear selector because it is a single speed transmission, but controlled by the same gear shifter as in a regular Ranger. The only difference is that “E” increases the amount of regen.

Since it is far more efficient to coast than to regen, I would hope that Chevy would create another drive mode that provides no regen when you let off of the accelerator.

It would also be great to have better control over regen braking vs. friction braking – a separate control and/or an indicator that shows regen increasing as the brake pedal position changes and the point when the friction brakes engage.

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Eletruk Says:
May 8th, 2008 at 8:47 pm

A couple of comments:
The Pulse & Glide work on the Prius because it turns the engine off. So you can “pulse” up to 35 mph and then the engine will shut off in the “glide” mode where you are not using any gasoline.This will work for even a standard vehicle, if you are willing to constantly shift into neutral and turn the engine off. I used to do this all the time with my Honda CRX (and manual transmission). Because of the Atkinson cycle engine in the Prius, it can restart in less than 1 revolution (not usually the case with an Otto cycle engine) so you get less of a savings in a regular car and need to be able to coast longer to justify the additional gas required to restart an Otto cycle engine.

I drive an EV daily, the 2000 Ford Ranger EV, and it doesn’t have a free/glide mode. It has 2 levels of regen, and neutral. I often go down slight hills where I would rather there was NO regen on and use the momentum of the truck to it’s full advantage, so I have to shift into neutral. I wish I had the equivalent of a MPG indicator in the truck so that I could find out if I were better off taking the regen, or coasting the additional distance gained. All I have is a rather non-specific “Economy” gauge that tells me I’m in the “green” or “yellow” area (Yellow is high current draw, often when starting). But I don’t get any real data to validate which is more efficient. The other option is to ride the accelerator so that the speed is held constant, but there again, I don’t get any realtime data on energy consumption.

So, for sure one of the things the Volt should have is the instantaneous “MPG” or “MPKWh” readout so you can learn the best way to maximize the battery. The “Pulse and Glide” driving method really won’t help the Volt, but a free/glide (non-regen) mode should be available as a standard piece of the operation parameters.

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matt986 Says:
May 8th, 2008 at 9:46 pm

Reading a few comments… this ‘thing’ is not a feature. It’s not something you can enable with a switch. It is NOT disconnecting the engine from the transmission.

This ‘thing’ is simply the point at which the throttle input is at equilibrium with the load on the engine. It’s that throttle position where if you push just a LITTLE, you start accelerating or if you let up just a LITTLE, the throttle closes, and the engine starts dragging.

You can’t ‘turn it on’.

Controlling that is all with your right foot.

How electric vehicles will work will be quite different, since the only drag the motor can induce is when regenerating. One COULD make a ‘feature’ where the motor doesn’t regenerate when the throttle is released, but that would depart from the traditional feel of the automobile. I figure, though, there will be some point in throttle position that will provide no thrust, but also no drag.

regardless..

IT’S NOT A FEATURE.

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Jimmy Says:
May 8th, 2008 at 10:43 pm

#48 Terry:

I agree with you…

“If you drive your Volt 40 miles or less, you use NO GAS – ever. ”

All we need is some kind of battery energy efficiency gauge and a display that shows how many miles until the gas motor turns on.

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Jim I Says:
May 9th, 2008 at 6:45 am

Did none of you read the original post?

GM refused to comment for “competetive reasons”.

People, I would have to assume that the engineers are so far ahead of us on all of this that when the Volt does make it to the showrooms, we are all going to look really silly!!!!

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Arch Says:
May 9th, 2008 at 9:00 am

When you take your foot off of the pedal on a serial hybrid you
will just coast. There is no drag from the electric motor until you
reverse the field current. I would bet they do that with the brake
pedal.

Take Care
Arch

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doggydogworld Says:
May 9th, 2008 at 9:31 am

A lot of discussion here is about Glide, which can maximize MPG (or MPkWh) on downslopes and aproaching stop signs and such. Glide is good, the Volt should make it easy to achieve Glide for drivers who wish to.

Pulse-and-Glide (P&G) is different, it works on flat ground with no stops. It works because gasoline engines are inefficient at part throttle. It only requires 3-4 kW to sustain 30-40 mph. The Prius’s Atkinson cycle engine is about 15% efficient at this level vs. about 33% efficient at 12 kW. P&G alternates between mild acceleration at 12 kW/33% efficiency and engine-off gliding (deceleration) with zero fuel burn. The engine still does the same amount of total work as driving a steady 35 mph, but because all fuel is burned at 33% efficiency instead of 15% you use less than half as much gas and you get something like 110 mpg instead of 50.

Prius P&G doesn’t really work on the highway because road load of 12 kW puts the engine in the high efficiency zone even at constant speed on level ground. Also the Prius can’t really Glide at highway speeds — the engine always rotates and causes drivetrain drag above 42 mph whether its running or not.

P&G does work in ordinary cars, but not as well because without Atkinson cycle efficiency is still pretty low at 12 kW. Normal engines also take a lot more energy to restart. Besides, it’s really dangerous to shut most car engines down while moving because you lose power brake and steering pressure.

P&G does no good in an EV because electric motors are highly efficient at pretty much all power levels. P&G would not help extend EV range in the Volt. Would it help get better MPG in extended-range operation? It depends. Like Prius, the Volt should require 3-4 kW at 30-40 mph. Like Prius, the Volt engine will probably be 15% efficient at such low power vs. mid-30s at 12+ kW. If the Volt engine is set to match road load, P&G might help. But the Volt control logic could easily force the engine to run at 12+ kW even when the car only needs 3-4 kW. Instead of accelerating the car, the extra 8-9 kW would charge the battery. After a while the engine would shut off and the car would drive as an EV again for a few miles. This is not as efficient as P&G because of battery losses. But it doesn’t require special driver skill and is much less annoying to other drivers.

A Volt with this control logic might achieve 85-90 mpg at a steady 35-40 mph. Prius could do the same thing, but their MPG would be lower because NIMH battery losses are much worse and their battery has much less usable energy so the engine would waste fuel with much more frequent restarts. Besides, long stretches of 35-40 mph driving are very rare, so why optimize for it?

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Mike756 Says:
May 9th, 2008 at 10:41 am

Jim #58

I’m aware of engine drag. There are other forces that act to slow the car down however, i.e. wind and rolling resistance. Do you have any numbers on the magnitude of these forces? The Volt will just slow down slower. I’m sure one could get used to it fairly quickly.

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BEK Says:
May 9th, 2008 at 10:45 am

It would seem in the best interest to add such a feature. Seems no one knows about the engine drivetrain and its ‘real feel’ yet.
Has anyone looked at the electric Delorean created by a father/son team.
Look at http://electricdelorean.com/

Now there’s some basic grassroots eletric car development. Good luck on this though. I am watching too….

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Glenn Says:
May 9th, 2008 at 11:20 am

I see your point in requesting this feature.

Where I live, if I want to go into town, there are two long downhill sections of highway. They are not steep, but the grade is just enough to keep the car going at highway speeds for for a mile or so. I have found that as I take the foot off the gas, the transmission engages to slow the car down (not a Prius). So I regularly pop the transmission into neutral to let the car glide for quite a ways until i reach about 40mph (limit 45) unless someone is behind me.

I’m not a hypermiler and I only do this on these two sections of highway, traffic permitting. I feel like I’m recouping a little of the fuel it took to get up the hills in the first place.

I’ve often wondered just how much fuel I’m saving (if any), and how my Volt will handle it in a couple of years.

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DaveP Says:
May 9th, 2008 at 1:13 pm

Well said, #88 doggydogworld. I expect that for the Volt, P&G isn’t going to do anything for mileage and I expect that the ICE in the Volt will probably run at ONE speed which has been tuned for maximum efficiency for dumping charge into the batteries. They’ve hinted as much; that it’s not going to deliver power to the drive motor, except through the batteries.
Given that, what IS going to do something for mileage in the Volt is to be able to control how much the ICE turns on to charge the batteries. Like, if you know you’re going to go down a mountain and the battery is low and the car is trying to turn on the ICE to charge it. Or if you’re almost home and the ICE kicks in to charge even though you only have a few miles left. By the time you get home if the ICE has recharged 50% of your capacity (20 miles worth) instead of just 2 miles worth (what you needed to get home) then you’ve wasted a lot of gas. Controlling THAT behavior is what is going to make Volt drivers act weird, not P&G!
I could totally see people pulling over and turning off their engines to stop the recharge cycle or something and then restarting and continuing!

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szyszek Says:
May 9th, 2008 at 1:20 pm

DaveP – ICE will NOT charge the battery. ICE is there to keep the battery from being depleted further. It is not designed to charge the battery at all, just to provide enough electricity for current usage.

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N Riley Says:
May 9th, 2008 at 2:08 pm

Computer-codger

I am sorry but the explanation of the 4 switch positions is as complex as the gas pedal positions when pressed. Look, have your normal speed control or cruise control switch that is exactly like now. Everyone knows how cruise control works. Add another button or switch to control the other “features” Let us not make it more complex than it should be. Your pressing slightly is not the same as my pressing it slightly and so on and on.

Now, I will read the rest of your post and the ones after. I just had to get my two cents worth in.

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N Riley Says:
May 9th, 2008 at 2:22 pm

Arch

I am with you. It seems that with the Volt if you want to coast, all you have to do is take your foot off the gas pedal. The computer should not engage regen, but allow the car to coast. If you want to put your brake on, regen starts. If you don’t want to slow down with the intend of stopping or reducing speed greatly (like coming up on something), just tap the brake. If you press the brake and hold pressure, you are signaling the computer to slow the car at the rate based on the pressure on the brake while starting regen.

This seems pretty simple. Am I missing something?

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Greg Says:
May 9th, 2008 at 3:11 pm

You guys don’t get it!!!!! It is like a one way clutch. When you let off the accelerator the engine does not slow car down. It is pretty simple.

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Mike756 Says:
May 9th, 2008 at 3:16 pm

I did Jim’s experiment on my way home from work with my manual transmission vehicle. I couldn’t tell the difference between the engine engaged or not. However, I notice the difference in rates of deceleration depending on my initial speed, the gear I was in and whether I going uphill or downhill. Despite the wide range of deceleration, I was able to dynamically process the information and adjust my behavior accordingly.

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noel park Says:
May 9th, 2008 at 4:16 pm

It seems like both modes have their place. If you were gong down a long grade, and the battery was not fully charged, I could see where you might want the regen to operate without necessarily putting the “brakes” on, to top up the battery. On the other hand, if the battery was fully charged, it might be good to be able to freewheel, to coast as much as possible and thus extend the battery range.

Maybe the software can somehow optimize this whole thing, but I’m sort of from Missouri on that.

We have a 3500 pickup with the Allison 5 speed. It has a sort of hill retarder function, which cannot be turned off. I hate it. Sometimes I am tempted to put it in neutral, as so many of us do with our manual transmissions. The Owners manual cautions you not to do so, in BIG BLACK LETTERS, and says it will void the warranty. That is partly because there is a good potential for going through the gate into reverse by accident. So I just bite the bullet and don’t do it, but it sure is irritating. I wish I had the 6 speed manual, but we got such a cheap deal at the end of the model year we had to buy it off the lot.

Just give us a simple switch to let it coast. I really can’t see myself searching around for the “sweet spot” with my educated (not!) foot.

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Mike756 Says:
May 9th, 2008 at 5:20 pm

” If you were gong down a long grade, and the battery was not fully charged, I could see where you might want the regen to operate without necessarily putting the “brakes” on, to top up the battery.”

So you would have some other doodad to control your speed? What is wrong with the brake pedal?

“On the other hand, if the battery was fully charged, it might be good to be able to freewheel, to coast as much as possible and thus extend the battery range.”

If the hills’s incline made you go faster than you wanted, you would still have to put on the brake. If it wasn’t steep enough, you would be using the battery.

When people drive, they control how fast they go, not when they charge a battery. Now I understand the geek impulse, because I have it, but I resist it when I need to.

Please just make the Volt drive like a regular car.

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gieso Says:
May 9th, 2008 at 5:50 pm

Is this “feature” just a simple display that tells the driver whether it is using energy (pulse), using no energy (coast) or Regenerating (slowing via motor)? Seems like a simpel screen that could be put on the display that could be shown (for the hypermilage folks) or turned off or replaced with a time/temperature/etc. display. Am I oversimplifying?

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Arch Says:
May 10th, 2008 at 2:59 pm

95 N Riley

The problem with most hybrids is that they can only use about 1/3 of the energy braking. You just cant add the juice to the batteries that fast. There is one hybrid the dumps the energy into a super cap.
That can be used for the next start up or bled off slowly to charge the batteries.

Take Care
Arch

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swimdad623 Says:
May 10th, 2008 at 4:11 pm

101 Arch

What you said is true for a hybrid like the Prius, which uses both a small battery (1.6KWH) and NiMH battery chemistry. It’s a different story with the Volt, which uses a battery 10 times as large with Lithium chemistry. The Volt battery should be able to capture 100% of the braking energy (up to the generation capacity of the electric motor). That won’t be enough to capture the braking energy for fast stops (since the friction brakes on a typical car can dissipate three times the energy of the motor), but for slow gradual braking the Volt should be able to capture most of the braking energy.

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Steve Says:
May 10th, 2008 at 6:49 pm

I don’t condone annoying everyone else on the the road with PnG. I’d rather the system be opitimized for real world conditions.

If you’re the only one on the road fine, but one of the biggest problems with traffic in not being able to maintain a constant speed. Everyone intentionally speeding up and slowing down is a recipe for disaster.

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Computer-codger Says:
May 11th, 2008 at 3:31 pm

N Riley #94,

I didn’t say it, but I assume a detent (a mechanism that temporarily keeps one switch position in a certain position relative to another) at switch position 3. There should be no guessing about where switch positions 3 and 4 are.

Also my proposed method of cruise control (see #80) has the same functionality as most current normal cruise controls, except that if you want coast, that is added. My Ford truck has accelerate and decelerate. My Buick has accelerate and decelerate (with one tap at a time for decelerate). But the response is relatively slow. I want decelerate to be much more responsive for coming down steep grades as well as in city driving. I also want a very steady speed control for switch position 2 when in cruise control, up and down hills. With the electronic controls available to the Volt this should be no problem. When in cruise control mode GM’s engineers can figure out when to coast automatically, I think. The problem of when to coast is not as certain when not in cruise control mode.

For the most part my proposed cruise control is very much like normal old cruise control. There are some slight differences that I propose for Volt cruise control. The driver should be able to start from a dead stop with the accelerate switch position 1. The driver should be able to slow down significantly with switch position 4. The friction brakes would be used for sudden braking and for the final stop.

By adding a hand brake control for paraplegic persons this car could be driven with hands only. This would be good, as there are thousands of people out there that require special engineering for their hand controls.

I am sure that GM’s engineers will figure out the best thing to do and whether to have a special control for coasting.

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John Says:
May 11th, 2008 at 4:31 pm

Just think of all the gas you are making other people waste when you are doing this constant speed up slow down. Gas cars don’t like that.
======================================================

Correct.

People should be thrown into jail for this dangerous behavior. It causes snarls, traffic jams and traffic accidents.

But then again, leftists never let human life get in the way of their harebrained schemes.

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Lee Says:
May 11th, 2008 at 10:34 pm

Does PnG = free wheeling = coasting? I don’t
know if it’s still true but in California coasting in Neutral using a Manual or Standard Transfission was illegal.

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noel park Says:
May 12th, 2008 at 7:27 pm

#106 Lee:

Maybe so, but I do it anyway, hee hee hee!

I don’t really care about “pulse and glide”. I just want to be able to maximize the fuel consumption on down grades. Based upon my experience with the Allison, I don’t trust somebody’s “algorithm” to do it for me.

I thought that calgaryvolt put it perfectly at #55. Of course, if Arch is right at #87, there is no issue here. I’m not sure I trust GM to make it that simple, but I sure hope so.

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Rob Says:
May 12th, 2008 at 9:18 pm

Pulse & glide is a way to maximize the efficiency of a internal combustion gasoline engine, which makes it’s best brake-specific-fuel-consumption at about 5/8ths throttle. You pulse at that throttle opening to accelerate the car in the engine’s most efficient load area, then glide down until you’re about to be rear ended. Lather, rinse, repeat.

This is going to be completely irrelevant in the Volt, because the ICE isn’t connected to the wheels. The pulse & glide of the ICE (if the GM engineers to their job of minimizing fuel consumption) will be built into the control software for the ICE.

Ok, some clever people will probably figure out at what load & rpm the electric motor is most efficient and then try to keep it’s operation in that range to maximize miles/kWh, but it should be in the 85%-90% efficiency range over the whole operating regime anyway…

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Randy Says:
May 13th, 2008 at 2:57 pm

I drive a Prius, the last 5 miles home are on a gentle slope, I would estimate less than 1%. I drive “normal” or use cruise control I get mileage of about 55 mpg. If I use PnG I average 99 mpg on the last 5 miles. My speed does not vary by more than 2mph, Same as with Cruise or not watching my pressure on the accelarator, It takes a very light touch on the pedal to get the proper feel for PnG.

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David Says:
May 15th, 2008 at 8:48 am

This might be good. Sounds like what my gasser does with the added bonus of not using any energy.

What I’d like to know is, will the glide part be regenerative?

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Jonathan Cassidy Says:
May 15th, 2008 at 11:14 am

The PnG and the glide point on a Prius is much more complex yet easy to use than is made of here.

I own an 06 Prius. I use this all the time. Much of the time I am not conscious of it. I do feel it. There is a surge when the dynamic generator comes off and you enter free wheel. It is not a big surge, but noticable since this car is so quiet.

The glide point, gap between power on and dynamic generator on, changes with different speeds. It disappears, for the most part, above 40 mph. The gap is larger at low speeds and gets progressively smaller.

This can be used on clear roads, light traffic and heavy traffic. It is fun to play with. You do not need to be watching the graph to do it, though this is of help when first trying it out. In heavy traffic glide is of use to smooth and calm your driving.

PLEASE DO NOT CRITICIZE THIS WITHOUT TRYING IT. Glide on a Prius, and eventually the Volt, will be just a spot on the accelerator pedal between power on and generator on. High end attention drivers will use it to great advantage, all others will use it without thinking or effort. If you do ever own a Prius or Volt. Take some time as a passenger and look at the display. You will see at times, on the Prius, the Energy Monitor shows no energy moving. This is the spot.

On a Prius if the ICE is off then this is actually free wheeling better than any other previous free wheeling situation.

I know these things I use it to the max for my situation, yet I never PnG.

I put on over 20,000 m/yr.

Jonathan Cassidy, associate broker
Prudential Manor Homes, REATORS
jcassidy@prudentialmanor.com

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does putting the prius shift in the b position recuperate more energy to the batteries than use of t Says:
June 4th, 2008 at 1:29 am

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Should the Volt Have a Free-Wheel Glide Pedal Position?

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