Invisibility:
Press R1, L1, L1, R2, L1, L1, L2.
Light Cars:
Press L1, R1, R1, L2, R2, R2.
Zero Gravity:
R1, R2, R1, R2, Up, Up, Up.
Decrease Time Warp:
R2, L2, L1, R1, Left, Left, Left.
Increase Time Warp:
R1, L1, L2, R2, Right, Right Right.
Wizard of Oz Mode:
R1, R2, R1, R2, Up, Up, Up a sound should confirm the cheat.
Use A Midnight Club Car:
First play Midnight Club and create a save. Now, play Smuggler's Run. Instead of loading the Smuggler's Run save, load the Midnight Club save. You'll now be able to use a car from Midnight Club.