Shoot Paintballs:

At the main menu press Up, Down, Left, Right, White, Up, Up. To shoot the paintballs press up on the D-Pad.

Mini Cars:

At the main menu press Up, Down, Left, Right, White, Down, Up.

Hardcore Realism Mode:

At the main menu, press Up, Down, Left, Right, White, Up, Down. Alternately, get a 100 point rating on a track to unlock the hardcore realism mode option for that track.

High Suspension:

At the main menu, press Up, Down, Left, Right, White, Left, Right.

Wire Frame Cars:

At the main menu, press Up, Down, Left, Right, White, Right, Left.

View Credits:

At the main menu, press Up, Down, Left, Right, White, Left, Left.

Race as Richard Petty:

Beat all heat challenges with a bronze or higher rating to unlock Richard Petty.