Depends on the airplane. Example for you. My Cessna 172 uses 7.25 gallons per hour and travels without considering winds aloft 120 mph+/-. I have 38 gallons of usable fuel on board. I have calculated my flight time from AR to FL in both car and plane. The pane is better milage and obviously faster.
True, but then 100LL is nowhere near 2 bucks a gallon, is it?