Research from Argonne National Laboratory shows that stopping and restarting a vehicle for as little as ten seconds uses less fuel than idling the engine. Start-stop systems increasingly available on some cars and trucks automatically shut down the engine to save fuel. The fuel used when idling varies by the accessories used (radio, lights, and fans), vehicle make and model, ambient conditions, and many other factors.
Fuel Use for Idling and Restarting
Note: cc = cubic centimeters. s = seconds.
Estimates from CSRA based upon work by Argonne National Laboratory.
Argonne National Laboratory, Which Is Greener: Idle, or Stop and Restart? Comparing Fuel Use and Emissions for Short Passenger-Car Stops, Argonne National Laboratory, 2013.