Switching off engine at red light

[Calvesy]

Has anyone worked out how long you can be stuck in a jam before it is more economical to turn of the engine and restart it when the traffic moves again? Surely it can't take much petrol to start a warm engine, but how much idle time would this volume of fuel equate to? I've got a 1.4 litre carburetted.

Answers most welcome from people who don't know, are guessing, or who have not taken the trouble to work it out.

[dilligaf]

Dont know, but the Honda due for release in the new year is fitted with some sort of gizmo where the engine stops when the driver stops at a red light. The engine starts again when the driver puts their foot on the accelerator. As Honda are being "eco friendly" I should imagine not a lot of fuel is wasted.

Well Calvesy, you invited people to guess and I have. No idea at all if it works. Just be a little embarrasing when the light goes green the engine wont restart.

[kempie]

Discounting hybrid vehicles, wouldn't switching off the engine whilst on the public highway fall foul of the law which requires that drivers must exercise proper (or full) control of their vehicles at all times?

[BillyBB]

VW made the Golf ECO which automatically turned off then on when you stamp the accelerator, this was diesel though.

To be worth bothering your engine should be off for thirty seconds, so I've heard. Railway crossings and traffic jams but not regular traffic lights.

[alan30]

In switzerland a few years ago when staying with a friend they and many other drivers switched off even at traffic lights. The explanation was that it was environmentally friendly rather than a fuel saving issue.

[Furby]

I believe that Cambridge now have a local bye-law that requires drivers of motor vehicles to stop their engines if likely to be stopped for 30+ seconds.