Quote:
Originally Posted by Thymeclock
Just out of curiosity, how many times in the course of a day do you shut off and restart your car at traffic lights?
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The typical break-even point for where more fuel is consumed idling than re-starting is on the order of 10 seconds. More for some cars, less for many.
In my CRX, I shut the car off probably a dozen times on the way to work, and a dozen more on the way home. Probably much more than that, as I frequently used pulse-and-glide, with engine-off coasting on the glide. I put about 40 thousand miles on the car doing that.
Wayne Gerdes over on cleanmpg.com has a couple of hundred thousand miles worth of re-starting constantly.
Wayne and I (not sure about PaleMelanesian) have a good bit of time spent in heavy traffic coasting with the engine off to stops. So far, nobody has tried to shoot either of us. Nor have we left a string of wrecks in our wake.
Some braking is unavoidable, especially in emergency situations. Most braking that most drivers do is avoidable, as long as you keep planning ahead. Gas-to-the-light-then-brake is immensely wasteful. Even gas-to-maintain-speed-to-the-light-then-brake is somewhat wasteful.
Most idling is avoidable, unless there are mechanical considerations that prevent you from turning the car off. (E.g., many automatic transmissions can be damaged by a lot of moving with the engine off; some cars dump a whole lot of fuel after a re-start; some cars have starters that are "iffy"; some cars have batteries that are too weak or small to keep their lights on at night for any real amount of time with the charging system off...)
Some of the choices are ones that you will not make. That does not mean they aren't feasible choices for other people.
-soD