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Received my new Volt this week and whilst I have not been able to crawl all over it yet (sh*t weather) I have been enjoying the drive.

One thing worries me though.

The low ratio gear setting provides increased regen braking which is good but I appreciate that this slows the car without showing brake lights which could (in certain circumstances) be bad.

Is it OK to switch between D and L on the hoof as situations allow, or is that not good for the drive train?
If I inadvertantly leave it in L during motorway driving could that cause problems?

Can anyone advise?

Regards,
Andy.
 

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Yes, you can switch between D and L anytime and at any speed: it is purely a change to the accelerator pedal mapping; there are no physical gears that change. L is fine right up to top speed of 100mph.

The question about brake lights has been discussed many times on the US forum. Apparently there is an internationally agreed standard for rates of deceleration where brake lights must show, or where brake lights may be shown even though you aren't physically pressing the brake pedal. The Volt regeneration in L is right at the low end of the range where it would be legal for the lights to come on but they aren't required, so although they could have made them light up if the regen was any less they couldn't have. I think it's no worse than engine braking in low gears, and if the car behind doesn't react you can always put your foot lightly on the brake pedal anyway.
 

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My first full day with the new Ampera and this was something I was worried about. If the vehicle behind seemed a bit close I was going back to D to be on the safe side, so swapping between L and D quite a lot.
 

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There's nothing to stop you dabbing the brakes in L if someone gets too close.

The EU doesn't allow brake lights for regen. Don't ask me why. Even the Tesla Roadster which has pretty strong regen (much more so than the Volt/Ampera) does not light the brake lights on the EU version. You really have to be careful with people following close with that car.
 

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dpeilow said:
The EU doesn't allow brake lights for regen.
Wow.. how stupid is that!?

So if you had a car with electromagnetic brakes instead of disc brakes where would you be?
It would seem much more sensible to have brake lights based on an accelerometer reading.

I can understand the EU saying no to all-ways-on brake lights when in Low Gear, but I dont think this is what we are talking about. unless there has been some kind of translation error or misunderstanding.

Personally I don't think that regen is any worse on the Ampera than engine braking on another vehicle, and that has traditionally not caused brake lights to show. I think its best to drive based on the distance you have not on the brake lights anyway... sometimes a slight tap on the brakes up ahead causes a cascade effect down a busy motorway. Its always best to pay attention and brake only if you need to not because a light flashes in front of you (I always read brake lights as a warning not an instruction).
 

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dpeilow said:
The EU doesn't allow brake lights for regen. Don't ask me why. Even the Tesla Roadster which has pretty strong regen (much more so than the Volt/Ampera) does not light the brake lights on the EU version. You really have to be careful with people following close with that car.
Correct me again if I'm wrong, but as I understand it we're talking about ECE Regulation 13-H and we have a "Electric regenerative braking system of category B" (which means an electric regenerative braking system which is part of the service braking system).
Paragraph 5.2.22.4 seems to be the relevant one:
Electric regenerative braking systems as defined in paragraph 2.17., which
produce a retarding force upon release of the accelerator control, shall
generate the signal mentioned above according to the following provisions:
Vehicle decelerations Signal generation
≤ 0.7 m/s² The signal shall not be generated
> 0.7 m/s² and ≤ 1.3 m/s² The signal may be generated
> 1.3 m/s² The signal shall be generated
In all cases the signal shall be de-activated at the latest when the deceleration
has fallen below 0.7 m/s²
 

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I have heard that the BMW i3 is going to have very strong regen - does anyone know if this is true?
 

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This issue regarding regen braking and brake lights is an interesting one.

I too agree that the Ampera regen braking is no worse than engine braking on a lot of cars and so the fact that the Ampera does not show brake lights when regen braking is not an issue for me. However, the general concept that cars with regen brakes do not have to show brake lights is basically flawed. I agree that the requirements to show brake lights should really be based on decceleration rate and there is no reason I can think of why this could not be done. If a particular model of car had regen brakes that caused a particular decceleration rate then it would require brake lights to be displayed when it did. Easy.

On the otherhand, it is down to us as drivers to ensure that our car displays the correct and sensible signals. If we know that brake lights are not displayed when slowing using regen and we feel it advisable that we show a brake light then we should just make sure we use the brake pedal to do so and that might mean coming out of L to D. I have not found it an issue at all but I am always aware of my brake light situation.

The OP described the L as a "low gear ratio"... this is not a good description. As has been said in another reply switching from L to D and back does nothing physical. It is a change to the computer mapping of the go pedal, nothing more, and so can be flipped between the two without limitation and at any time. The Ampera has no gears in the traditional sense.
 

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Having driven some performance cars in the past, a friend was suprised that I now had an "automatic". I am not sure I was that successful in my explanation that it wasn't an "auto" and that the usual issues with "autos" (wrong gear, slow downshift, etc.) just didn't apply...
 

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Only had the car for 3 days but already I'm finding the 'L' setting useful for short local journeys where I live, where speeds are usually not more than 30mph on suburban roads and there are plenty of shallow rises and falls on my usual haunts, so plenty of regenerative potential. Its also quite satisfying learning the gentle accelerator action when lifting off to control the rate of retardation.
 

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Do you see an advantage in driving in 'L' most of the time, except if you were going down a hill ? particularly with comments on no brake lights.
I tend to drive in 'D' most of the time and believe that I get the same regen benefits as long as I brake gentley without using the friction part of the brake.
Any thoughts ?
 

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neil said:
Do you see an advantage in driving in 'L' most of the time, except if you were going down a hill ? particularly with comments on no brake lights.
I tend to drive in 'D' most of the time and believe that I get the same regen benefits as long as I brake gentley without using the friction part of the brake.
Any thoughts ?
I've experimented a bit with driving on my local roads in L and using the accelerator to control the slowing down of the car- its rather like driving in third all the time on a manual car. I'm lucky here in that the local roads aren't that crowded so I don't usually have someone else driving right up my back...the brake lights aren't really an issue. The main disadvantage I've found is that if you do take your foot off the accelerator, the slowdown is pretty sudden which detracts from the general air of smooth progress that the car provides. I found I got bored with that and I've gone back to mainly using D and braking gently as you say.
 

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I'm finding that with the colder weather (<10 deg C) the regen in L is a lot less. Anyone else?

Personally I drive in L all the time. I prefer the 1 foot driving and if I could I'd have even more regen, like with a Tesla. Once you've experienced that, the Ampera's regen is quite tame.
 

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Something that most people don't realise is that it is easier to get maximum range out of the Ampera in D rather than L if you know what you are doing... I can see you all looking confused. Isn't L there to increase regen braking and so increase range? Well, yes but not for the reason most people think.

As others have said.... L & D are nothing more than different computer settings for the GO and STOP pedals. D uses more aggressive acceleration settings and softer regen braking whereas L uses softer acceleration settings and more aggressive regen braking.

What actually determines range is not the computer settings but how energy is used, saved, recovered and wasted as you drive. In theory, you can get exactly the same range in D as you can in L... it just means you would need to drive the car in a slightly different style in each but with careful pedal usage you can acellerate and brake to exactly the same degree in either mode.

So how does L give us more range than D?

It is all about the way we drive. In D it is easy to accelerate harder than we need to, or even want to, thereby wasting energy. Also in D we have to consciously press the brake pedal to slow and so we get less energy recovery just by lifting off the GO pedal. This means that unless we carefully accelerate less and brake more we will waste energy.

Conversely, in L it is easy to accelerate slowly and we have to consciously acellerate harder and we automatically get more regen braking just by lifting off the GO pedal meaning we have to work less hard at energy recovery.

These factors result in us getting max range more easily in L than in D.

However, rather perversly, if you do drive very consciously and are good at hypermiling you are more likely to get better range in D rather than L. This is because as an expert hypermiler you won't be prone to over-acellerating so won't waste energy there and as there is less regen braking in D it means that it is easier to coast thereby not braking at all and that is the most efficient way of driving. The absolute maximum range would be if we didn't even need to brake at all! Clearly not practical except on a test track. So we must drive with consideration of other drivers and with safety in mind but that doesn't mean we cannot find that coast point and not brake much when it is safe and sensible to do so and in doing that you will get better range.

It takes practice.

As for whether to drive in L or D? That is very much a personal choice and factors such as your personal driving style, mood, conditions, terrain etc will mean you prefer one over the other in certain circumstances but remember... with good anticipation and smooth driving the actual range in D or L won't be a lot different.

It is fun though isn't it :)
 

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Great explanation Paul.
 
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