At the white Infogrames screen press Up, Down, Triangle+Circle. The words "Lock Off" will appear.
Now quickly hold one of the following cheats until the Infogrames logo disappears. A message will confirm entry:

Left + L1 Unlimited Time
Left + L2 Narrow Tracks
Left + R1 Rollercoaster Track and Jeep
Left + R2 Restart Race
Left+R1+L1+R2+L2 All cheats

Hidden Jeep:

Hold Left + R1 until the Infogrames logo disappears.

Rollercoaster Style Track:

Use the cheat to get the hidden jeep, then, when in the game, go to either Championship or Time trials, and go to Sweden. Go to Stage 1, and a screen should say, loading ??? stages. You will then be racing on a Roller Coaster style track.