Think about hybrids. The ICE is shut off for longer periods of time because of the electric motor to propel the car, but it is because of the time that the ICE is not running that saves gas. This has also been researched many times.

I'd take back that neg rep if I could, but don't bash things you don't know about. It may seem like a trivial thing that would only save you a couple of dimes, but I've seen some of the lines around Cobb get to the point where you will be in line for 45 minutes. If people did this while in line it would save a significant amount.