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.
Successfully complete arcade mode with all four characters to unlock Nihonmaru.
Successfully complete arcade mode with all four characters to unlock two bonus trailers in score attack 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.
Press Start to pause game play, then press A + X + B + Y.
First pause the game, Then press up,down,left right, and start at the same time. This should work if it goes back to the main screen.
On the Trailer Selection screen, hold: L + R + X + A + B + Y + Start.