To enable any secret option, go to the main menu and press one of the following combinations:
All story mode chapters: Down, Left, Up, Right(2), Up, Down, Left
All tracks in arcade mode: Up(2), Left, Down, Left, Right(2), Up
All cars in arcade mode: Up, Down, Right(2), Left, Up(2), Down
Arcade championships: Right, Left, Up, Right, Down(2), Left(2)
Multi-player championships: Left, Down, Left, Up, Right, Left, Down, Right