Previously when most cars depended on carburettors to blend fuel and air for use by the engine, this particular myth probably had a bit more substance to it. However, modern fuel injection—which is used by most cars now operating on the road—allows ignition to occur without having to expend any more fuel than is required to keep a car idling. If you really want to save on petrol costs, consider turning off your engine whenever your automobile is going to be remaining motionless for more than approximately 30 seconds.
