“Whenever vehicles must accelerate, energy must be supplied (from the gasoline). When vehicles decelerate, this kinetic energy is lost and must be resupplied when resuming motion. Any situation where a vehicle can coast (for example to arrive in motion at a traffic light as it just turns green) will save much more energy (gas) than one might think. Thus, drivers should drive strategically. Look at the traffic lights far ahead and adjust driving speeds accordingly. When you see a red light, coast until you see it change. When you must stop, coast to diminish your speed as much as possible before braking. Cities should better design traffic lights to maintain flow and momentum of the maximum number of vehicles that travel at a designed speed.” (emphasis added)
Read the whole thing.