We have "flying cars" - they are called "aircraft". Most of them still use tires on the landing gear.

Back on topic - The main problem that I see with fuel prices is that the demand is largly inelastic. I still need to drive to work and back 5 days a week if gas costs $2/gal or $4. I still need to heat my house. I still need to eat.

Sure, I can conserve slightly at the margins. If I cut out my Sunday afternoon drive with the family, I save a few gallons. If I turn the thermostat down from 68F to 66F, I save a few gallons. But for the most part, my fuel needs are fixed.