Idling is linked to increases in asthma, allergies, heart and lung disease and cancer.

Idling gets ZERO miles per gallon.

Idling for 1 hour burns nearly 1 gallon of gasoline.

Ten seconds of idling can use more fuel than turning off the engine and restarting it.

Letting your car idle vs turning it off:

If you know you are going to idle for 10 seconds or longer… turn it off. For every two minutes a car is idling, it wastes the same amount of fuel as it takes to travel about one mile.

In the winter let your car warm up:

If you must “warm up” your car 30 seconds will do the trick. The best way to warm up a car is to drive it. So be a little easier on the pedal for the first few minutes of your drive if you want your car to warm up. You will also cover some ground this way instead of getting zero miles per gallon while idling.

Turning off the car uses more gas than just letting it idle:

Component wear caused by restarting the engine is estimated to add $10 per year to the cost of driving, money that will likely be recovered several times over in fuel savings from reduced idling. The bottom line is that more than ten seconds of idling uses more fuel than restarting the engine.

This article is summarized from Consumer Energy Center