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I have been using low gear to increase energy regeneration (drive more efficiently). But it slows the car down more quickly when you take your foot off the accelerator (as expected). This means I must always keep my foot on the accelerator and cannot "glide" in a normal sense of coasting. So at least on a mostly flat roadway with few stops, I might be using MORE energy in normal driving instead of saving energy. I am using energy when I would normally use none (i.e., when I could coast).

I will note that Low gear may be good during highway driving where most of the time there is little coasting (excepting on downhill grades). It is especially good when making lots of right angle turns (city driving in neighborhoods), where there are lots of stop signs or traffic lights, and on highway exit ramps since it slows down the car a fair amount making normal braking (mostly) unnecessary. You can use the steering wheel "regen" paddle less or not at all when in low gear.
 

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It's a complicated situation. Even more so with the Volt, which has blended brakes, so in typical conditions the first part of the brake pedal is also regeneration.

As you've suggested, staying on the accelerator longer and then regenerating harder doesn't save energy over gliding at a slower pace - if your patience and the traffic situation supports the slower pace.

I like L because it gives me easier control over the car's speed - in most normal conditions I don't need the brakes except right at the end. If I want to float, I just feather the accelerator to get the rate I want.
 

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I have been using low gear to increase energy regeneration (drive more efficiently). But it slows the car down more quickly when you take your foot off the accelerator (as expected). This means I must always keep my foot on the accelerator and cannot "glide" in a normal sense of coasting. So at least on a mostly flat roadway with few stops, I might be using MORE energy in normal driving instead of saving energy. I am using energy when I would normally use none (i.e., when I could coast).
Driving in D is slightly more efficient. I highlighted the apapro text from your original post. The reason is as long as you keep your foot (or cruise control) on the throttle, you're spending energy fighting friction. Getting off the throttle earlier will eliminate this energy consumption.

Coming out of a standard transmission I'm not adverse to shifting the car to L and using the regen paddle to bring it to a near stop when needed, but if I have the space and traffic won't be impacted I leave it in D and just let off the throttle early.
 

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Most of my driving is around town so I primarily use L. It works especially well in stop and go traffic where it slows the vehicle sufficiently that I barely have to touch the brakes. For highway and Interstate travel I put it in D and use the regen paddle as necessary.
 

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The best thing about the gen2 Volt is the seamless blending of regen braking with the brake pads which the car does automatically. There's no difference between driving in "D" using the brake pedal and driving in "L" using the accelerator and brake pedal. Both use regeneration first, and both have the same maximum amount of regeneration braking which is the amount of braking applied by the regen paddle.

It is more efficient to slow down at the minimum deceleration since there are losses in charging the battery and speeding up again. So in theory, you can get slightly better efficiency by driving in "D" to minimize acceleration/deceleration. In practice, the efficiency differences are swamped out by driving style. You can efficiently use either "L" or "D"; just minimize your acceleration/deceleration. And if you need the maximum regen braking allowed, sometimes the regen paddle is also helpful.
 

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You don't want to be regenning for the sake of regenning as it's not efficient. If you have to slow down anyway often (like in stop and go city driving) L is a good idea and any coasting you do can be done by feathering the pedal. In highway driving much of your slowing down will be coasting (assuming you are looking far enough ahead and not just staring at the car in front) and any greater deceleration handling by the regen in the braking. You don't want to trade kenetic energy for regen unless you have to. When talking about this I'm always reminded of a taxi right I had from Calgary airport to home one night long ago where the new Canadian driving the taxi would gun the engine to speed then coast down then gun the engine again thinking that he was getting better mileage coasting, not realizing he more than lost that in accelerating back up to speed after every coast. Also made for a very uncomfortable taxi ride.
 

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Keep in mind that the actual quantity of regen you put back into the battery as you slow down (say, from 40 mph to 20 mph as you approach a traffic light) or come to a stop (say, from 45 mph to a complete stop at a stop sign) may not be capable of being influenced by your choice of D, L, or paddle. A higher level of regen creates high regen for a shorter period of time (slows the car faster), a lower level of regen creates low regen for a longer period of time (takes longer to slow the car).

Use regenerative braking as braking... your choice of regen level should be influenced by its ability to allow you to drive as you wish. There will be many times during a trip when traffic conditions require you to slow down (sometimes to a complete stop), and then accelerate back up to speed. By using a regen level that allows you to minimize the reduction in your car’s speed as you coast toward the light, waiting for it to change, or to minimize the number of times you need to come to a complete stop before the light changes, the less energy you will need to use to accelerate back up to speed, and thus the more energy you will have to use to maintain your speed (a more efficient use of battery power).
 

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Queue the next DvL debate! The only good thing is that we're slightly more civil about it than the Dem-v-GOP debate!
(By the way, I'm with @obermd, for what that's worth):rolleyes:
Regardless of the actual answer, driving in L is nauseating for some people, including my wife who is prone to motion sickness.
 

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Regardless of the actual answer, driving in L is nauseating for some people, including my wife who is prone to motion sickness.
If she doesn't have a problem with D and braking equally hard then it isn't a problem with driving in L - it's a problem with the way the car is being driven in L (most likely suddenly getting off the accelerator completely.)
 

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If she doesn't have a problem with D and braking equally hard then it isn't a problem with driving in L - it's a problem with the way the car is being driven in L (most likely suddenly getting off the accelerator completely.)
Put a Gen 2 Volt on cruise control on a hilly back road at moderate (50-60 MPH) speeds. In L the car jerks on and off the throttle to maintain the set speed. In D the car is much smoother getting on and off the throttle, but at the expense of accelerating down hills. I've heard the 2019s are smoother on and off the throttle in L than prior years.
 

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Put a Gen 2 Volt on cruise control on a hilly back road at moderate (50-60 MPH) speeds. In L the car jerks on and off the throttle to maintain the set speed. In D the car is much smoother getting on and off the throttle, but at the expense of accelerating down hills. I've heard the 2019s are smoother on and off the throttle in L than prior years.
Interesting. My first generation certainly held speeds under cruise on hills, but I don't remember it being jerky. Maybe that's related to the chuggle and the hassles of a permanently connected engine. Do you see this on gas, on electric, or both?
 

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Interesting. My first generation certainly held speeds under cruise on hills, but I don't remember it being jerky. Maybe that's related to the chuggle and the hassles of a permanently connected engine. Do you see this on gas, on electric, or both?
Both, but it's more noticable on electric as the gas engine is slower to respond to the ECU's throttle inputs.
 

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Driving in D is slightly more efficient. I highlighted the apapro text from your original post. The reason is as long as you keep your foot (or cruise control) on the throttle, you're spending energy fighting friction. Getting off the throttle earlier will eliminate this energy consumption.

Coming out of a standard transmission I'm not adverse to shifting the car to L and using the regen paddle to bring it to a near stop when needed, but if I have the space and traffic won't be impacted I leave it in D and just let off the throttle early.
At the risk of kicking off the aforementioned debate, the rest of your post doesn't support your thesis. You said that driving in D is more efficient, and then go on to (correctly) explain that a certain pattern of acceleration/coasting/deceleration is more efficient.

That pattern may or may not be more natural to a driver driving in D, but it's easily executable in either gear.

To the best of my knowledge there is no evidence that one mode is inherently more efficient, nor any technical reason that it should be. Having said that, the car's responses do encourage driving habits that are different, and those habits can be more or less efficient.
 

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Somewhere I read that a Volt engineer stated that coasting was the most efficient, followed by driving in D (closest to coasting when foot is off the accelerator pedal), finally driving in L. Of course not all driving conditions are the same. Some report slightly higher efficiency when driving in L. The efficiency difference between driving in D and L is probably not worth worrying about. I prefer to drive in L for my local driving because it enables me to use the foot brake pedal less often. I prefer to drive in D on the highway (when I remember to do so.)
 

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Driving in L is more for convenience (in heavy traffic) than for energy efficiency.

The volt has higher efficiency when there is less acceleration and deceleration (for hilly roads, resisting acceleration in uphill also helps greatly). The L mode decelerates the car, which naturally creates a speed variation and reduces the energy efficiency.

But if you can feather your foot to the accelerator paddle with a less pressure, you can potentially achieve a constant speed in L-mode, but the dynamic range of such pressure is very small compared to the D mode.
 

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In my Gen1 I use L mode exclusively. I tried regular D mode, but found that the car just coasted too much requiring me to step on the brake pedal more often. Considering that the brake pedal uses regen for a small portion of it's travel, I believe I exceeded that level more often than not requiring the car to use the standard friction brakes more often that I ever did in L mode. Because of this, I achieved less efficiency in D mode than L mode. I also just like L mode driving much more. I drive like I normally drive, I feather the throttle to manage my decelleration and I never worry that I'm stepping the brakes too much so I know I'm capturing as much regen as I can.

This is what works for me, but it may not work for everyone.
 

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Interesting. My first generation certainly held speeds under cruise on hills, but I don't remember it being jerky. Maybe that's related to the chuggle and the hassles of a permanently connected engine. Do you see this on gas, on electric, or both?
I put several thousand highway miles on my 1st Gen Volt as well using cruise. It was never jerky on hills.

Via TechTom https://gm-volt.com/forum/showthread.php?26217-Driving-in-L-vs-D&p=327673#post327673

I've got some actual data (from DashDaq) to answer parts of this question, and it backs up what most have already said on this thread.

This first one is a test on a hill that I measured watt-hours consumed in both L and D. The overall difference is not significant, but L does seem to be less efficient when using the same non-aggressive driving style for each.




However, driving aggressive can make L more efficient. As shown in this next measurement. Green is consumed current while accelerating, and red is generated current while slowing down. When aggressively braking, L-regen is engaged quickly as you lift off the accelerator and move your foot over to the brake pedal. Where as in D, regen is not as much during that transition to brake.



Either way... driving less aggressive is the most efficient method... L or D.

Tom
 

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The way I've always put it as a short-hand is: the more g's you feel, positive or negative, the less efficient you are being.

To a first approximation, energy consumed goes as x (distance); to a second approximation, it goes as x' (velocity); and to a third approximation it goes as x" (acceleration, positive or negative). By the time you get to fourth-order effects it's pretty much just rounding error.
 

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The way I've always put it as a short-hand is: the more g's you feel, positive or negative, the less efficient you are being.

To a first approximation, energy consumed goes as x (distance); to a second approximation, it goes as x' (velocity); and to a third approximation it goes as x" (acceleration, positive or negative). By the time you get to fourth-order effects it's pretty much just rounding error.
Back when cylindar deactivation was all the rage in the automotive press, BMW actually did some testing. What they discovered was that accelerating right at the threshhold where the three deactivated cylindars would activate was the most efficient way to get cars with this technology up to speed.

In the Gen 2 Volt this translates to keeping the KW usage below 20, especially when accelerating from a stop while running on ICE in any of the charge sustaining modes (Hold, Mountain, Depleted). When the car finally fires up the ICE to recharge the battery back to the set point it will be a more efficient use of the engine than using the engine to accelerate the car.
 
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