No roof flaps:
 Note: This procedure involves editing a game file; create a backup 
 copy of the file before proceeding. Use a text editor to edit the 
 "nr2k2" file in the game folder. Go to "PLAYERS", go to your player, 
 then go to "PLAYER" (not PLAYRECS). The first number you see should 
 be "1". Change it to "0". When you play the game and go backwards at 
 a fast enough speed, you will fly into the air and possibly do some 
 flips.