"The classic argument about the flying car is that it ends up being a crummy airplane and a crummy car," Seeley says. But in his concept, rather than replacing either cars or commercial aircraft, it will be made specifically for trips between 40 and 500 miles.

Skies could then transform into highways for relatively slow-moving air vehicles--and eliminate traffic jams. "You have an unlimited number of freeway lanes and an unlimited number of overpasses," Seeley says. "The three-dimensional, full-breadth aspect gives you overwhelming capacity," thanks to a layered web of traffic flying between 3,000 and 5,000 feet. To hop into the fast lane, don't veer to the left; shoot to the top. Drivers may not even need to train as pilots. Work at NASA's Langley Research Center shows that a computer-controlled intelligent flight deck can help anyone with a driver's license pilot an air vehicle safely.