>They burn a lot of gas per hour, but they also go faster than a car and so per distance efficiency is about the same as a gas car.

A cessna 172 burns 8 gallons an hour in cruise at 125 mph. A generic sedan at 30mpg burns 2 gallons an hour at 60mph on the highway.

The calculations do not work for small planes. The energy to go double the speed is not double the energy.