Bonus parking levels
Successfully complete each of the four parking levels to unlock an additional parking level. Successfully complete the bonus parking level to unlock a sixth parking level.

Nihonmaru (Japanese version)
Successfully complete arcade mode with all four characters.

Haul an Ice Cream TruckIce cream truck
H hold L + R + X + A + B + Y + Start at the same time to haul ice cream truck on the pick a trailer screen.

Unlock all tracks, stuff and disable time
At the main screen hold L and press A, Y, X, B, Left, Start.

Bounus Trailers
Successfully complete arcade mode with all four characters to unlock two bonus trailers in score attack mode, versus mode, and arcade mode (if the Nippon Maru is selected).

Lizard Trail
Successfully complete the game with all five trucks (Asphalt Cowboy, Stream Line, Long Horn, Highway Cat, and Nippon Maru).

Nippon Maru
Successfully complete arcade mode with all four characters.

Full pause screen
Press Start to pause game play, then press A + X + B + Y.

Cheat mode
Hold L and press A, Y, X, B, Left, Start at the main menu to unlock all trucks, all tracks, and disable the timer.