I think one of the coolest things that Chevy had in its display at the Texas State Fair auto show was this little matte colored version of the new small car called the Sonic. The first time I saw it sitting there, I thought it was a clay reproduction of the Sonic used for the design process. Then it started whirring and lifted into the air. It turned out that it was a full-scale model of the new Sonic that was controlled and is controlled by a big RC controller like an RC airplane.
I asked one of the people on the team that was controlling the fling Sonic about the car and he told me it was made from specialized and very lightweight foam and was sealed to keep the helium inside the car from leaking out. The car held somewhere in the area of 5-6 cubic meters of helium according to the source.
The car appeared to be neutrally buoyant and the only thing that would make the car move other than the little electric engines on each side was the stiff breeze from the massive AC system inside the show hall. The propellers were placed on little electric motors that allows for full directional control for the flying car. Each of the electric motors were on carbon fiber booms hooked to the control system and battery pack under the car. Check out the video to see the car flying around the show hall and the photo gallery to get more detail.