Based on a worksheet developed by Argonne National Laboratory, the idle fuel consumption rate for selected gasoline and diesel vehicles with no load (no use of accessories such as air conditioners, fans, etc.) varies widely. Both compact sedans with 2.0 liter engines each consume about the same amount of fuel at idle (0.16 and 0.17 gallons per hour respectively), despite differing fuel types. By comparison, the large sedan with a 4.6 liter engine consumes just over twice as much fuel at idle. Of the remaining vehicle types listed, the transit bus consumed the most fuel while idling at nearly 1 gallon per hour (gal/hr). The gasoline medium heavy truck category with a gross vehicle weight (GVW) of 19,700-26,000 lbs. consumed more fuel at idle than the diesel medium heavy truck category at 23,000-33,000 lbs. GVW.

Fuel Consumption at Idle for Selected Gasoline and Diesel Vehicles