DARPA says that "the objective of the Transformer (TX) program is to demonstrate a one-to-four-person transportation vehicle that can drive and fly, thus enabling the war fighter to avoid water, difficult terrain and road obstructions as well as IED and ambush threats.
The vehicle will be capable of driving on prepared surface and light off-road conditions, while flight functionality will require Vertical Takeoff and Landing (VTOL)."
The problem with the current Mine Resistant Ambush Protected (MRAP) vehicles is that they sometimes get stuck, as some battlefields become difficult due to variable landscapes. So a flying car would resolve all these problems, as long as it could vertically take off and land anywhere and run on different terrain.
The program DARPA is developing has three important objectives: creating a "robust vehicle design that maximizes military utility" at a low cost, developing the necessary technology to make such a vehicle possible and build a car which could handle all the challenges of a battlefield.
In order to be able to build such a vehicle, technologies like adaptive wing structures, ducted fan propulsion, composite materials, hybrid electric drive and advanced batteries must be further researched.