Which do you think uses more fuel: idling or turning off the car and restarting it? Many drivers believe it’s better to idle.  The fact is, just 10 seconds of idling uses more fuel than a single engine restart.  Even short periods of idling add up over time to wasted fuel and large amounts of harmful greenhouse gas emissions.  If you’re concerned about the engine wear and tear of restarts, don’t be. The potential wear of restarting is insignificant compared to the amount you’ll save in fuel. Unless you’re in traffic, restarting is always better than idling.