Enter these codes in the name box. you must quit and start a new race to change. After entering the code choose your car, select time trial from the game mode screen, go to Corsica and chose any course. You will be on a track you have never done before. It may not be on tarmack.

Hidden track 1:CBLC
Hidden track 2:CBLCA
Hidden track 3:CBLCB
Hidden track 4:CBLCC
Hidden track 5:CBLCD