*EDIT* I think I found the problem, when the car does the flipping it clips into the ground, is it possible that the game detects that something is in the floor and knocks it out? Instead of returning it to the ground it might just get launched into the air. Also might be important to say the glitch doesn't kill you when you land, infact, the worst damage would be just having another flipped over car!
It would be really cool to see this glitch found and patched, and as mentioned earlier, here is the screenshot. (Use the town in the picture to get an idea of how high we were launched!)