Does stop-start technology really save fuel?

I have a new Mercedes with an 'Eco' button, which cuts out the engine when stationary to save fuel. Surely turning the engine on and off engine wastes more fuel then just idling briefly?

Asked on 17 June 2013 by NFB

Answered by Honest John
Not once the engine is hot. But it can be very irritating. The Mazda 6 Skyactiv with i-eloop has by far the best stop start system.
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