Private aviation often plays victim to bad weather and hefty storage and maintenance fees. If light aircraft could double as road vehicles, pilots would have a more practical, safer way to fly.
The Transition has wings that extend and retract electronically, allowing it to take to the air and then drive home from the airstrip on city streets (where it can hit 65 mph and gets 35 mpg). Says Terrafugia  CEO and CTO Carl Dietrich: "People like to call it a flying car, but it's really a street-legal airplane."
FAA standards require the Transition to weigh under 1,000 pounds when unoccupied. Carbon fiber and titanium, used for the fuselage and frame, have a higher strength-to-weight ratio than steel or aluminum.
Despite its shortcomings, the Transition does solve one of the biggest barriers to personal aviation: high storage costs. It fits neatly into a standard home garage, saving owners up to $1,500 a month on the cost of a hanger. It also puts to good use the U.S.'s 5,200 public-access airports, most of which see too little traffic to justify car-rental kiosks or cab lines.
1. Pass future flight and drive tests.
"We have to do things during testing that no pilot in their right mind would do," Dietrich says. The Transition is designed for casual cruising, but upcoming tests include aggressive acrobatics.
2. Ensure its street and sky legality.
Federal motor-vehicle standards never imagined something that could drive and fly. "It either complies with multipurpose vehicle standards," Dietrich says, "or we've gotten exemptions." Terrafugia is working with insurance providers to design plans for the Transition.
An initial run of 10 Transitions will roll out to customers once compliance testing is completed. After that, Terrafugia can ramp up production into the hundreds.