When approaching a red light...

[burritos]

Let's say you're about 1/4 mile away and going about 40 mph. If you let go of the accelerator and just coast you'll still have to stop. Do you brake more aggressively down to say 5 mpg thus allowing you to time the green light and coast through it? This technique might peeve off people behind you who are trained to accelerate to red light and idle. But really, you're doing them a favor by saving them gas.

[icarus]

<div class='quotetop'>QUOTE(burritos @ Nov 11 2007, 01:26 PM) [snapback]538043[/snapback]</div>

Let's say you're about 1/4 mile away and going about 40 mph. If you let go of the accelerator and just coast you'll still have to stop. Do you brake more aggressively down to say 5 mpg thus allowing you to time the green light and coast through it? This technique might peeve off people behind you who are trained to accelerate to red light and idle. But really, you're doing them a favor by saving them gas.
[/b]

In order to use the least amount of fuel, (which of course is the whole point!) you should try to time the light in such a way as to keep as much momentum as possible, coupled with good light timing skills. This way you avoid as much of the acceleration that needs to burn fuel to regain that momentum. I believe that anytime your on the brakes you are loosing the game. I know that there are people who will argue that the regen braking just gives it back to the battery. The problem is twofold. One is that it is not a zero sum game. It always takes more energy to get back up to speed than you can put in through regen. Second, you have no control (Little or no) over how much the regen braking is working and how much the friction brakes are working. Clearly, if you are loosing heat (energy) through the friction brakes you are lossing the game.

I try to stay off the brakes as much as possible, being courtious to other drivers. Having said that, coasting to a light that MAY have to stop at suggests that you get off the throttle as early as possible, driving in warp/stealth until you KNOW you have to stop, then get off the trrottle completely and let the regen start, and get on the brakes only as needed.

Just one man's opinion.

Icarus

[john1701a]

Lifting your foot off the accelerator instructs the smaller of the two electric motors to capture that excess energy... which results in a slowing of the vehicle. (green arrow to battery on the Multi-Display)

If it is too soon to begin slowing, just reduce pressure on the accelerator instead. (no arrow to the battery) This is a glide, which is less intrusive on speed.

Stepping lightly on the brake instructs the larger motor to generate electricity from slowing.

[burritos]

<div class='quotetop'>QUOTE(icarus @ Nov 11 2007, 04:50 PM) [snapback]538052[/snapback]</div>

In order to use the least amount of fuel, (which of course is the whole point!) you should try to time the light in such a way as to keep as much momentum as possible, coupled with good light timing skills. This way you avoid as much of the acceleration that needs to burn fuel to regain that momentum. I believe that anytime your on the brakes you are loosing the game. I know that there are people who will argue that the regen braking just gives it back to the battery. The problem is twofold. One is that it is not a zero sum game. It always takes more energy to get back up to speed than you can put in through regen. Second, you have no control (Little or no) over how much the regen braking is working and how much the friction brakes are working. Clearly, if you are loosing heat (energy) through the friction brakes you are lossing the game.

I try to stay off the brakes as much as possible, being courtious to other drivers. Having said that, coasting to a light that MAY have to stop at suggests that you get off the throttle as early as possible, driving in warp/stealth until you KNOW you have to stop, then get off the trrottle completely and let the regen start, and get on the brakes only as needed.

Just one man's opinion.

Icarus
[/b]

Yes. Using the brake is losing the battle I agree. Is it a bigger loss than being stopped though. Let's say the scenario above is inevitable through no fault of your own(ie. visibility, the road being on a curve, unfamiliarity with stoplight patters). Do you slow down losing energy to win at the potential loss of starting from a dead stop?

[icarus]

<div class='quotetop'>QUOTE(burritos @ Nov 11 2007, 02:29 PM) [snapback]538074[/snapback]</div>

Yes. Using the brake is losing the battle I agree. Is it a bigger loss than being stopped though. Let's say the scenario above is inevitable through no fault of your own(ie. visibility, the road being on a curve, unfamiliarity with stoplight patters). Do you slow down losing energy to win at the potential loss of starting from a dead stop?
[/b]

I think the answer is, if you Have to stop, ie red light or stop sign, then slowing down effeciently is best. If you MAY have to stop, it seems that coming to a complete stop is worse than not having to stop at all, so slowing down, but not too far, leaving open the possibility of accelerating up again, rather than coming to a complete stop too soon. Does that make sense. In other words, while sitting stopped at a light burns no fuel, starting up from the light does. Conversly, slowing up to the light, letting it change and accelerating from a rolling start has got to be more effecient, regardless of any regen. Add in the potential regen, and I still think that keeping the car moving is the best bet.

Icarus

[burritos]

<div class='quotetop'>QUOTE(icarus @ Nov 11 2007, 06:07 PM) [snapback]538087[/snapback]</div>

I think the answer is, if you Have to stop, ie red light or stop sign, then slowing down effeciently is best. If you MAY have to stop, it seems that coming to a complete stop is worse than not having to stop at all, so slowing down, but not too far, leaving open the possibility of accelerating up again, rather than coming to a complete stop too soon. Does that make sense. In other words, while sitting stopped at a light burns no fuel, starting up from the light does. Conversly, slowing up to the light, letting it change and accelerating from a rolling start has got to be more effecient, regardless of any regen. Add in the potential regen, and I still think that keeping the car moving is the best bet.

Icarus
[/b]

I think so too. Now. In this specific scenario, do you do this all the time? or only when no one is behind you?

[F8L]

Since I am terrible at this sort of thing another idea:

If you get stuck having to come to a full stop. Pop it in EV mode and get back up to speed, or as far as you can, in EV mode then go back to gliding? I have a series of stop signs and lights that I ALWAYS have to stop for on the last leg of my route.

[icarus]

<div class='quotetop'>QUOTE(burritos @ Nov 11 2007, 05:21 PM) [snapback]538130[/snapback]</div>

I think so too. Now. In this specific scenario, do you do this all the time? or only when no one is behind you?
[/b]

Unless you want to be percieved as one of those granola chewing, birkenstock wearing, long haired Prius driving people who are responsible for the cloud of smuf oozing over the horizen, (Oh! I guess that IS me!) i try to give some consideration to the folks behind me. The is there are a lot of terrible drivers out there, and I won't give a lot of courtesy to the tailgating guy behind me, but I do use common sense and courtesty

Icarus

[hobbit]

This is only one of many reasons why the world needs many more
roundabouts. Then you'd be able to 100% predict that you'd have to
glide down to at most the circulation speed, and possibly stop and
wait to enter from there [but the braking/regen efficiency hit from
25 is far less than from 55]. With sufficient sightline distance
you'd be able to modulate slightly one way or the other to let you
merge gracefully in most of the time.
.
_H*

[efusco]

Hobbit, I too love roundabouts..but hadn't considered the fuel efficiency benefits until you mentioned it....