When approaching a red light...

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

 

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.

 

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

 

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.

 

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

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

 

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*

 

There's been a bit of discussion about roundabouts/rotaries/circles
over on cleanmpg, where mr.bill forwarded a couple of really good
links. When I'm coming up to one, I usually take the opportunity
for a nice, long, predictable glide... without worrying if the light
is going to change or not.
.
_H*

 

My inclination is to slow down by braking so that I don't have to stop at the light. Wen I start to slow down, I find that most large cars and trucks will pull up about 3 inches from my car's rear end and sit there until we get to the light. What they want to do is go fast up to the light, stop quickly, and sit. So I ease into slowing down and see what the person behind me does. If they back off a bit, I'll slow down to an appropriate speed. However, if they just jam onto my car's rear end, I'll do my best to accommodate them and not slow down as much as I'd like to.

Avoiding an accident due to someone else's frustration and potentially fatally slow reactions is way up there on my list, even above getting more mpg. Assuming that the rear end huggers don't hit me, their frustration level is up from not being able to speed up to the red light. I've seen people do some pretty silly stuff when their frustration level is up.

-Roger

 

When I see a red, I always ease off and try to coast to the lights, regardess of those behind. Mind you, I am talking of a distance of just that 1/4 mile that burriotos put forward. I do not try to break and then creep up on the lights, nor do I leave a huge gap in front of me.

I find that a number of other drivers in my area tend to do the same. I have had a couple of occassions where I am very happy with the driver in front of me who seems to also be trying to minimise the impact of the light on his FE, although I have noted others behind me not so happy.

As a side issue, how do you react when you have a driver in front of you, in the same scenario, slow down immediately and sort of creep up to the lights, ready to floor it when they change green?

 

It's not a question of "slow down and then creep". The right thing
to do is a slowdown toward the light at as CONSISTENT a rate as
possible, i.e. constant rate of deceleration, which is the easiest
to predict and react to. You are much LESS likely to get rear-ended
by doing this. The person stuck to your butt is probably the type
who wanted to blast up and jerk to a halt at the end, but if he was
allowed to do that he'd be much more seriously endangering the cars
behind *him* as would you if you did it. You can be predictIVE and
predictABLE in these scenarios and that's best for all concerned
whether they know it or not.
.
_H*