Don’t keep your car running if you’re not moving. First, avoid prolonged warming up of the engine, even on cold mornings - 30 to 45 seconds is plenty of time. Don’t know if whether it’s more cost effective to keep the car running or turn it off – if you’ll be idling for more than a minute, it’s better just to turn it off since one minute of idling consumes the same amount of gas as starting the engine. Routinely shutting the car off rather than allowing extended idling could improve your gas mileage by 19%. Remember that the next time you’re backed up in the drive-through lane.