Saving gas
Idling your vehicle for 10 minutes uses ...
... as much fuel as it takes to travel 5 miles.
Idling for longer than ten seconds uses more fuel than restarting the engine does. When you combine idling your vehicle with running the air conditioner, it uses an extra 13 percent more gasoline and releases 13 percent more tailpipe pollution.
(Source: TheTransportation Program of Natural Resources Canada's Office of Energy Efficiency (OEE) & the Vermont Agency of Natural Resources)