Ford Levacar.

From the Fantastic Plastic webpage for the Ford Levacar:

“Ford Motor Co.’s Levacar Mach I appeared in the Ford Rotunda in spring 1959. A full-sized prototype, this was an one-man “flying car” that was “levitated” several inches off the ground by three powerful air jets located on the bottom of its chassis. Planned to be powered by a small-scale turbojet engine, the Levacar was purportedly designed to reach a top speed of nearly 500 mph! The only question was: How do you steer the damned thing???”

[LINK] [VIA] Boing boing.