All Cars
     At the Title screen, press Up, Down, Up, B, A, Left, B, B, Down.

or
     In  10  Year Championship mode, finish in first place every year.
You'll  receive a bonus car after each year you finish in first place.
After completing the mode, and every year in first place, you'll get a
bonus track.

All Seasons
     At the Title screen, press Up, Left, Down, Right, B, A, B, Right,
Down.

Change Frame Rate
     At  the  Main  Menu,  press Up, A, Down, Down, Left, Right, B, B,
Down  to change the Frame Rate to 60 FPS. Or, press Up, A, Down, Down,
Left, Right, B, B, Up to change the Frame Rate to 30 FPS.