Infinite nitros:
Pause the game, hold R1 + R2 and press Down, Down, Down, Circle, Circle, Circle.

Play as Boss car:
Hold L2 and then press left, right, down, up, square, circle, X, triangle.

Unlimited Cash:
Hold L2 and R2 and press left, left, right, right, square, square, circle, circle.

Infinite weapons:
Pause the game, hold R1 + R2 and press Left, Up, Right, Down, Square, Triangle, Circle, X.

Small Cars:
At the main menu, press and hold L1+R1, then press Down, Down, Down, Circle, Circle.

Invisibility:
During game press pause, now hold R1 + R2 then press Left, Up, Right, Down, Square, Triangle, Circle, and X.

Large Cars:
Hold L2 + R2 and press Up, Up, Up, Square, Square at the main menu cube. A sound will confirm correct code entry.

Hint:
same thing goes for small cars only hold L1 + R1, Down, Down, Down and Circle, Circle.

Alternate Car Colors:
Hold R1 and press Square. Triangle, or Circle at the main menu cube to display 3 additional color schemes.

Voodoo Car:
At the main menu, press and hold L2 then press Left, Right, Down, Up, Square, Circle, X, Triangle