1) Do it in the snow to cushion your landing.
2) Drive fast enough to really get some hangtime.
3) Use the right horn.

Added: This VW bus is pretty nuts, too:

Ken Block jumps his Subaru WRX Rally car 171 feet off a dirt jump. The car flies so high it nearly hits the camera:

Flying rally cars are not anything new, though… Click here to view the whole post.