In the options menu hold L1+R1 and enter the following:

Triangle, Triangle, Square, Square - Blow up vehicles in one hit

Triangle, Triangle, Triangle, Triangle - Fastest cars

Square, Square, Square, Square - Faster cars

Triangle, X, Triangle, X - Infinite car health

Square, Square, Square, Triangle - Press horn to do a huge leap in your car

Circle, Circle, Circle, X - More camera angles

Circle, X, Circle, Triangle - Grid mode

X, Circle, X, Circle - All reward Cars

X, Square, Square, Triangle - Credits

Triangle, Triangle, Circle, Square - Speedometer display

Circle, Circle, Triangle, Square - Red Brick Car

Triangle, Circle, Triangle, Circle - Tripping mode