While at the Games Title Screen:

Master Code: 
R1, R1, Up, Down, R2, R2, Left, Right

$10,000 In Car: 
Up, Down,Left,Right,Up,Down,Left,Right,R1,Left,Left 

Pit crashing: 
Go into the pits at the end of pit lane. You can crash into cars, which shows on the tack.

Bonus options: 
The following bonuses can be unlocked during game play by doing well and earning points:

AI Vengeance: AI cars retaliate when hit. 
Front Wheel Drive: Car has front wheel drive. 
Hardcore Physics: Hardcore realism. 
Horn Ball: Press Up to shoot a paintball. 
Horn Mortar: Press Up to shoot an explosive mortar. 
Insane Racecar: Press Up to jump. 
Mini Cars: Smaller cars. 
Monster Cars: High suspension. 
Oh Dear: One car on track replaced by monstrous-sized crew member. 
Super Draft: Faster draft speed. 

Race as Richard Petty: 
To race as Richard Petty you must get a bronze or better in all the Beat the Heat challenges.