@Robin: BMW were actually the first manufacturer to introduce engine stop-start on their vehicles.
I wonder how turbo'd BMW's cope with stop/go technology?
Surely spinning up the turbo and then cutting the power at the next junction that comes up isn't a good thing for Turbo longevity!!!!
Why? With a small first stage turbo it will be barely spinning at idle anyway; stopping the engine will just wind it down, and restarting will just wind it up (very very quickly - quicker than it will take you to get your foot off the clutch). With new(ish) ceramic bearing technology which is practically frictionless it won't detract from the life of a turbocharger. Remember, there have been stop-start diesels for ages now (at least two years).
That's not to say I
like stop start - if I want to turn the car off, I'll turn the car off; but with fuel injection and other technologies it won't add any extra wear to an engine.
I'll leave it to the hair-shirt brigade.