Article:The electric Chevrolet Volt produces realistic returns

[wainair]

Calling out the smack talk!

http://www.thenational.ae/lifestyle/...listic-returns

It's to bad he didn't know how to save some charge using MM so he wouldn't have gotten the 9.0L/100km in the city that he did after his charge ran down. Had he started in MM at the start of his day and gone back to normal mode when he left the highway he would have been able to avoid the bad city gas mileage.

[Steverino]

Many reviewers do not use or understand MM and L.

[therfman]

Many reviewers do not use or understand MM and L.

Nor should they need to. The car is designed to be driven like a normal vehicle, and it was driven in such a way.

[Kup]

Nor should they need to. The car is designed to be driven like a normal vehicle, and it was driven in such a way.

Agreed. Shoot, I've had the Volt for almost 5 months and I can't really think of a time when it would have made sense for me to put in MM. Of course, I'm in the relatively flat DC area and am in EV mode almost 90 percent of the time anyway. I'll cut the reviewers some slack.

[Bob_Livonia]

Nor should they need to [understand MM and Low]. The car is designed to be driven like a normal vehicle, and it was driven in such a way.

Agreed wholeheartedly. You don't get energy for nothing. Electric propulsion from the grid is much more efficient than electric power produced by an internal combustion engine. Mountain mode is time-shifting the availability of battery energy at the expense of running the gas engine much harder to produce much more expensive kilowatt hours of energy. When the engine is screaming in MM, do you wonder why "normal" cars have the engine run at low RPM's for maximum fuel economy, and why with heavier cars and SUV's, they don't just use a small engine and gearing to really wind it out instead of having a larger engine? Unless I'm running the Indy 500 (and the engine only has to last 501 miles), I don't want the engine on my Volt winding out producing 20 MPG just so I can use the battery later. (The normal mode switches the engine off whenever practical).

Likewise with Low - the vehicle has regenerative braking. If you brake reasonably to keep the meatball green and in the center, you aren't really getting a whole lot out of low that you wouldn't have got out of normal braking.

The article linked is a good one.

[Steverino]

I live in flatland as well. I don't use MM to go up mountains, nor to recharge a depleted battery. With my commute I will always end up using some gas.

If did not to use MM at the beginning of my return trip, I would deplete the battery on the highway where it is least efficient, and end up using the gas engine in the stop and go city end of my drive where the ICE is least efficient.

For those advising against using MM, please explain why I should use the ICE in the city and the battery on the highway.

By switching to MM during the highway leg of my homeward travel, I am able to reserve the battery for the last 14 miles of stop and go city driving where the battery is a far better choice than the ICE. As a result, I get better mileage. Ditto with L. Plus using L I don't need to use my brakes as much meaning longer brake life.

[wainair]

I'm not saying to game MM to recharge the battery(I'm not convinced there is anything to gain doing that not to mention I suspect it could decrease the life of the battery because you are effectively quick charging the battery like L3 charging), I'm saying use MM like Steverino does, using MM like hold mode. Go into MM right from the start to save charge to use it when it is more efficient, on the surface streets. When you do that the engine doesn't rev excessively, it runs on electric just as it normally does and it goes into CS mode earlier to keep the battery at a higher SOC. In MM it just does it earlier at 45%SOC instead of at 20%SOC when the car would go into CS mode under Normal Mode. So then once I'm off the highway I can go back into normal mode and still have 14 or so miles left to drive on electric at low speeds where it is the best. Then I'm not getting 9L/100km(26.1mpgUS) in stop and go traffic like the reviewer was. I'd be burning fuel at 5.8L/100km(40mpgUS) at highway speed which is much less.

[Steverino]

Exactly, wainair.

When you know you will be exceeding the battery range, and you have a combination of city and highway travel, use MM to strategically use the battery when it is best to do so (low speed city roads), and use the ICE when it is best (high speed highway). Much like the "battery off" mode that the Ampera will have for this scenario. And this is exactly the scenario described by the author of the article you posted.

[Bob_Livonia]

So then once I'm off the highway I can go back into normal mode and still have 14 or so miles left to drive on electric at low speeds where it is the best. Then I'm not getting 9L/100km(26.1mpgUS) in stop and go traffic like the reviewer was. I'd be burning fuel at 5.8L/100km(40mpgUS) at highway speed which is much less.

It may be a surprise to you, but you're driving on electric all the time - the only difference is whether the electric energy was generated by the grid or by the gas engine. There is also energy put back into the battery from regenerative braking, which contrary to popular opinion, works whether deceleration is controlled by using low range, or by the brake pedal, which gives better driver control (and a brake light to warn other drivers).

So the total energy for the trip (i.e., sent to the drive wheels) is the same regardless. The only question is where (and at what RPM) the gas engine is most efficient at producing electricity.

Now, if you drive over 70 MPH on the highway, you are quite possibly better off using the engine then, rather than later in the city if given the choice. The reason is that in CS mode over 70, "the small electric motor is sometimes connected to the planetary, which means the gas engine can - and does - send some power to the wheels for efficiency's sake" (about a 15% improvement in efficiency over pure electric propulsion). [recall the talk of some saying "see, the Volt really is a hybrid rather than an EV"]. (http://gm-volt.com/forum/showthread....s-of-operation)

In Europe, there is a "hold" mode to allow the battery charge to be reserved for the central city, where more governments are limiting or heavily taxing emission-producing vehicles, even adjusting their tax by the time of day. The EPA didn't like the idea of hold mode, but mountain mode (not quite the same) slipped in, based on needs for long sustained grades. (Michigan and surrounding states don't have mountains, so I never use mountain mode).

But also consider that in stop and go traffic in CS mode, where the battery charge is sustained the calibrated level, the engine generally shuts off below 25 MPH, is almost always off when stopped, and is sometimes off at sustained speeds of 40 MPH for up to a mile.

But I don't see how doing a quick (L3?) charge using mountain mode with the engine revving continuously at at 4 grand is good for the engine nor the battery.

[Bob_Livonia]

Now, if you drive over 70 MPH on the highway, you are quite possibly better off using the engine then, rather than later in the city if given the choice. The reason is that in CS mode over 70, "the small electric motor is sometimes connected to the planetary, which means the gas engine can - and does - send some power to the wheels for efficiency's sake" (about a 15% improvement in efficiency over pure electric propulsion). (http://gm-volt.com/forum/showthread....s-of-operation)

It just hit me that to gain an advantage from this high-speed CS mode, you (1) have to be breaking the speed limit in most states, and more importantly (2) your MPGe efficiency drops with speed, with a downward inflection point at 70 MPH. (http://gm-volt.com/forum/album.php?a...achmentid=2533).

So if you really care about maximizing your range and minimizing fuel used (and avoiding speeding tickets), simply slow down and leave the thinking to the Volt's smarts.