Use the following names to get the desired effect:
Effect - Code
CUAQUEZ - Challenge mode.
MACHOMAN - Unlock all cars.
MADDUCK - Trophy mode.
MORATA - Unlock all tracks.
OOOH SI - Championship in professional mode.
PACMAN - Unlock all game modes.
PEROPAVO - Unlock all cars, tracks and modes.
THEMASTER - Unlock all arcade mode bonuses.