It's impossible. It acts as if you hit the car, even though you are 20-30m over.
Give it a try on... the track.. forget the name... (where you go through a tunnel, up-hill, down-hill, tight slow curve all with a forest around it, mean anything to you???) take a sunday-cup or so, take a powerfull car that is quite heavy, i.e. Vanquish, start the race and go inverse. Wait for them to be around the tunnel and try to time it so you smash them on top of the huge hill. You'll see that what happens is:
1. The first car flies up 20 good meters.
2. When a car drives under that car, it is stopped as if the car flying is a wall from ground to sky.