Pushing military technology is the purpose; the primary goal is a vehicle capable of both driving on the road and flying. Such abilities would allow the vehicle to cross difficult terrain more efficiently, especially considering the vertical take off and landing capability the design brief calls for. Other bullet points include low cost and maximal military utility.
Flying cars have been developed before, all with some level of compromise. Even now, there's the Moller SkyCar, and the Terrafugia Transition; both are nearing feasible production, albeit with large, six-figure price tags. If you've developed a car to fly over traffic jams like we all wish for, you've got less than a week to register with DARPA for the January 14th kickoff.
[Source: Inside Line | Image: Hanna-Barbera]