Question: how much fuel does diesel use at idle?
Answer: Idling a heavy-duty truck consumes about 0.8 gallon of fuel per hour. Even when diesel costs as little as $2.50 a gallon, fuel for one 10-hour rest period will cost $20. Typically, a long-haul truck idles about 1,800 hours per year, using about 1,500 gallons of diesel.