Question: how much gas does a vehicle use idling?
Answer: Generally, an idling car uses somewhere between 1/5 to 1/7 gallon of fuel per hour. Compact cars that carry a 2-liter capacity engine burn around 0.16 – 0.3 gallons of gas on per hour basis. A large sedan, on the other hand, with a 4.6-liter engine, burns approximately 0.5 – 0.7 gallons of gas while idling.