The dream of the flying car simply won't go away. Glenn Curtiss rolled out Autoplane in 1917, the first attempt at such a vehicle, and the design trend continues to this day. Terrafugia's TF-X is a newer hybrid design from its older Transition models, but the basic design still breaks down to a vehicle that functions as both an automobile and an airplane.
The popular dream of flying cars, however, lands us slap-dab in the middle of hoverboard country, where we're forced to contemplate the bugbear that is antigravity technology. While the ability to manipulate antigravity would transform transportation immensely, the subject is largely taboo in research circles due to numerous hoaxes and unfounded claims. This doesn't mean serious minds aren't interested. Between 1996 and 2002, NASA's Breakthrough Propulsion Physics Project explored the possibilities of antigravity.
Researchers in France did create a skateboard that can levitate a couple inches off the ground, thanks to some insanely cool superconductor technology [source: Smalley]. Sure, it can only go in a straight line and at a height of a few inches, but who cares: "Back to the Future" is nigh!