Enter the following cheat codes in the "Enter Code" screen of the "Options" menu to enable them. Enter the code again to disable them.

Password Effect

Up left down right up left down Aggressive Opponents
B, Up, -, +, 1, Up, + Granite Car
-, Up, -, 2, -, Up, - Helium
A, B, A, Up, Left, Down, Right Invulnerability
B, Up, -, 2, B, Up, - Monster Truck
Up, +, Up, Right, -, Up, - Moon Gravity
A, -, +, Down, Up, +, 1 Overkill
Up right down left up right down Pacifist Opponents (Other Racers dont attack you)
Left, A, Right, Down, B, Up, - Psychedelic
B, A, Left, Down, -, Up, - Tiny Opponents
B, A, Down, Up, B, A, Down Unlimited Boost
1 2 1 2 B A + Unlock the Last 3 Cars

Unlock Class 4 (Mirror) - In order to unlock Class 4 (Mirror) in Championship mode, complete Class 3, Championship 9 with a ranking of 3rd or higher.

Class 4 (Mirror) Complete Class 3, Championship 9

Unlock Concept Art Movie - In order to unlock the "Concept Art Movie," complete Class 3, Championship 8 with a ranking of 3rd or higher. In order to view the movie, select "Movies" under the "Options" menu.

Concept Art Movie Complete Class 3, Championship 8

Unlockable Racers - All championships must be completed with a ranking of 3rd or higher to unlock the corresponding racer and move onto the next championship.

Booster Mbube Complete Class 2, Championship 6
Colonel Colon Complete Class 3, Championship 4
Delila Complete Class 3, Championship 3
Denise Mobile Complete Class 3, Championship 6
Esther "Rev" Reddy Complete Class 3, Championship 7
Gothorm Danneskjblo Complete Class 3, Championship 2
Grey Ghost Complete Class 1, Championship 3
Kellie "Gearbox" Kalinkov Complete Class 2, Championship 4
Mariana Zanja Complete Class 3, Championship 5
Nitro Venderhoss Complete Class 2, Championship 5
Pitter Pat Complete Class 3, Championship 1
Prince Kabala Complete Class 2, Championship 3
Rosey Blaze Complete Class 1, Championship 1
Snake Oiler Complete Class 1, Championship 2
Sonic "Boom Boom" Renaldi Complete Class 2, Championship 2
Taejo Togokahn Complete Class 2, Championship 1