Driving around town in "L"?

[gadgeTT]

Hi All,

I took my second test drive in a 2012 Volt yesterday after which I put down a deposit and placed an order for a 2013. My current car - a 2012 VW Eos is my first car with automatic rather than manual transmission. Sure, it's a DSG, but it's still an automatic. I really miss driving stick and especially being able to engine brake. Yesterday, I put the Volt in "L" instead of "D" and let the more aggressive regen braking work - it really felt like engine braking in a stick-shift car, plus it recouped more energy for the batteries.

My question is this - is there any disadvantage in either normal driving efficiency or otherwise, to driving around town in "L" rather than "D"? Can I drive around town in L and then switch to D on the highway to use the less aggressive regen? I realize that the Volt has a CVT transmission, so what else does the "D" versus "L" affect aside from the regen pattern?

Also, I know I can answer this next question when I get my 2013 in a month or so, but do the brake lights come on when the Volt is slowing down due to regen? I know that the Tesla Model S uses a g-force sensor to determine when the regen braking is severe enough to warrant warning other drivers, but the BMW electric car always turns on the brake lights when you lift off the accelerator pedal. What does the Volt do? I presume it behaves the same way as driving a stick shift car using engine braking in that the brake lights only come on when pressing the brake pedal and if so, I'm OK with that.

Anyway, thanks in advance for the help on the L versus D question.

[saghost]

There's no downside to driving in L all the time, if you like the pedal mapping - because the remapped pedal for additional regen is the only thing it does. There are no mechanical changes, and it doesn't change any of the Volt's other decision maps. Actually, there's a poll floating around, and last I looked, something like 2/3 of us drive the car in L all the time. You can always achieve the same results in either D or L (in D by lightly pressing the brake you get the same regen as L gives; in L by feathering the gas you can get the light regen from L) and thus the same efficiency can be achieved using either one - it's just a convenience thing for the driver. I especially like L when dealing with freeway stop and go traffic.

The Volt's transmission only operates as a CVT at lower to moderate loads at freeway speeds. Below that, the main drive motor is in a fixed gear relationship (the ring gear is locked by a clutch, so the sun-planet carrier is a fixed ratio) of 7:1 to the wheels - think of it as a big V6 (273 ft lbs) that's always in 2nd gear. Even at high speeds, if you floor it the car will return to this configuration - the engine and MG A can't produce as much torque as MG B does. That return is the only gearshifting you'll ever feel the Volt make - there's a slight hesitation before the rest of the power comes on as it stops the ring gear - kinda feels like a fast automatic transmission kickdown surge.

The brake lights do not come on in L - the Volt complies with federal standards for deceleration and brake lights, and L is near the maximum deceleration allowed without brake lights.

edit: Here's the Poll - currently 58% are driving in it all the time:

http://gm-volt.com/forum/showthread....ion-of-Threads

[jkoeller]

I drive in 'L' all the time. The only time I drive in 'D' is if I'm on the highway for an extended period of time (30+ miles), simply because I prefer its normal coasting characteristics on the hwy.

Congrat's on ordering your Volt!!

[BAZINGA]

Walter, again thanks for educating this old dog. I've owned my Volt since 3/31 and have felt what I thought was as slight downshift but always dismissed it as unlearning 45 years of driving and or my imagination.

I myself bounce back and fourth between driving in D or L depending on conditions.

Thanks for the info. To the OP welcome aboard, you'll love the Volt even more the longer you drive/owen it.

[Koz]

What Saghost said. The only real difference is in how well you can control your foot. Driving in D makes it easier to drive more smoothly and coast with minimal regen. Both can be be accomplished in L as well but you have learn the pedal feel and control your minor foot motion very precisely.

It's nice to regen in L via lift off since you know for sure the friction brakes aren't being applied. In D, like Saghost explained, you can get regen only with the brake pedal but the car doesn't give any feedback to tell you when you've gone too far and engaged the pads. It would be nice if GM adds red imaging to the wheels on the power flow screen to indicate friction braking is occurring.

[Kup]

In the early months of 2011 there were quite a few threads regarding "L" vs "D". I was one of the early "D" proponents who liked to coast and then manually shift to "L" when I wanted the extra regen without using the brakes. However, after reading this forum more and trying the driving in "L" all the time, I've come to the conclusion that, for me, it is better to drive in "L" all the time. With very little practice you can learn to feather the pedal so that it operates closer to a normal vehicle in that you can coast at freeway speeds and then essentially down shift when the traffic slows down.

The good news is that if you like the shifting experience there is no drawback to having it in "D" and coast when you want and then manually "downshift" to "L" when you want the extra regen, even if it is dozens of times on a trip. In essence there is no downside or wear on the transmission if you are regularly going between the two modes.

[Steverino]

I used to use L all the time, but I now do the combo. D for its smoothness, and L for engine braking. I use cruise control as much as possible with D, then when approaching stopped/slowing traffic if flip off cruise, "downshift" into L. I will also feather my slowing by shifting back and forth between D and L. I am getting pretty good at getting to the car stopped in front of me just as the light changes so I maintain rolling inertia, if only 2 mph.

Just returned from a 32.9 mile round trip with 18 miles left on the battery. That's an effective range of 50.9. All intra city driving with stoplights, 30 mph, 35 mph, and 40 mph speed zones, with the bulk at 40 mph, windows open.

Had one guy pull along side and tell me, "I want your car!" Too late, my wife already has dibs. :-)

[marksvolt]

I've made a couple of longer trips of mixed suburban & highway driving in "L" now. On 100% Battery I got 54.5 on one and just over 55 miles on the other. In both, I drove pretty carefully, coasting where I could and accelerating at speeds that I would have cursed other drivers for when I was young. (Having other people on your tail makes stretching the battery juice when accelerating or braking a little less fun).

So, I am sold on "L" for most driving, with the exception of driving on limited-access highways when traffic is light- "L" slowed me a bit too fast sometimes on the highway.

Questions for the experienced here:

-Is it ever bad for the hardware to drive in "L" in "Sport" or "Mountain" Modes?
-I imagine that the terrain has a lot to do with the answer to this, but in general, is "L"/Normal always the best combination for mileage on 100% battery?
-Does coasting in "D" and braking lightly provide about the same amount of regen compared to "L" and little or no braking?
-When the ICE kicks in, do you still drive in "L" and try to help charge the battery with moves to maximize regen? It seems from the "Power Flow" graphic, there is still significant regen going on even in ICE mode. Does regen during ICE travel increase gas mileage- or just a little extra battery when driving under 25 mph?
-I have yet to drive with the traction control off- does that affect driving in "L" much?
-If you are out on a nice dry road surface is there a power benefit to turning off the traction control at all?

More questions to come, I am sure, as I try to figure this all out.

Mark

[saghost]

I
Questions for the experienced here:

-Is it ever bad for the hardware to drive in "L" in "Sport" or "Mountain" Modes?

The hardware is designed for it. There should be no issues from using any of those settings in any operating condition. The Volt takes care of itself.

-I imagine that the terrain has a lot to do with the answer to this, but in general, is "L"/Normal always the best combination for mileage on 100% battery?

It's not the mode, it's what you do with it.

Seriously, any combination of D/L and drive mode can be used to achieve exactly the same effect. As a general rule, lower speeds are more efficient, and floating/sailing is more efficient than regen is more efficient than friction braking.

-Does coasting in "D" and braking lightly provide about the same amount of regen compared to "L" and little or no braking?

It can be. The Volt chooses when and how to cut the friction brakes in as well as regen, and the process isn't obvious to the user. L regen is around half of the regen the car is capable of. If you like driving with both feet/left foot braking, make certain you're completely off of the gas pedal before you hit the brake. If the gas is depressed at all, the car bypasses regen and goes straight to friction brakes.

-When the ICE kicks in, do you still drive in "L" and try to help charge the battery with moves to maximize regen? It seems from the "Power Flow" graphic, there is still significant regen going on even in ICE mode. Does regen during ICE travel increase gas mileage- or just a little extra battery when driving under 25 mph?

I don't drive in L for the sake of maximizing regen - I drive in L for my convenience as a driver - it allows on foot driving for most conditions. Yes, I do it when the engine is on. The one drawback to this is that if you get completely off of the gas in L below ~60 mph, the car will shut the engine down regardless of SoC. Regen power gets fed into the same mix with engine power - it'll turn the engine off sooner, turn the engine on a little later, or delay in revving up if there's some extra power in the battery. Thus, regen power does increase mpg directly.

-I have yet to drive with the traction control off- does that affect driving in "L" much?
-If you are out on a nice dry road surface is there a power benefit to turning off the traction control at all?

I don't believe that traction control has much impact on dry roads, unless you're flooring it from a stop in a turn. I'm not sure if turning off traction control will affect the "low traction" warning which shuts down regen when a wheel starts slipping. If it did, that'd be the only affect traction control has on L

More questions to come, I am sure, as I try to figure this all out.

Mark

We're all still learning about this car. It gives me a hobby...

[drbruns]

Driving the Volt in Sport mode and L is a real blast. It will take you about 2 minutes tops to get the hang of L. Let us know what you think after a week of driving.