Waiting at the train tracks? Waiting in the driveway for your buddy to grab his clubs? Backed out of the garage to rack a bicycle?
It’s time to bust the common myth that you waste more gasoline starting your car than you do idling. Turns out the break point is about 5-10 seconds, as in if your car is going to be idling more than about 10 seconds, you’re wasting gas. Shut the engine off and turn it back on when you’re ready to move:
Third, regarding gasoline consumption, engineers now estimate that only if an engine is restarted within 5 to 10 seconds of being turned off is it more fuel efficient to leave it running. This leads to the 10-second rule mentioned above: If it looks like you will be idling for longer than 10 seconds, turn off the engine and restart when you are ready to drive.
The average person spends about 16 minutes a day idling, which amounts to around $116 a year for a 4-cylinder engine.
Oh, and on that other myth that you’ll just be wearing out your starter:
Second, starters are stronger and more reliable today than they once were. Research reported by Natural Resources Canada (Canada’s equivalent of the US Department of Energy) suggests that the increased wear and tear on the battery and starter that may result from more frequent restarting of the engine due to the elimination of voluntary idling costs less than $9 US per year.