Enter in cheat Menu: 

All Cars : 
YAYCARS 

Fast Start: 
IMSPEED 

Unlocks all tracks and mini games: 
MATTL66 

Unlocks all tracks and mini games: 
IF900HP 

Inf Boost: 
VROOOOM 

Unlocks Art: 
CONC3PT 

Unlocks Movie Clips: 
WATCHIT 

unknown: 
R4MONE 

Unlock Master's Speedy Circiut and Master's Countdown Cleanup: 
TRGTEXC