SD cars:
Hold X and press Right(2), Up(2), Down, Left, Down, Left, Right, Up, Down, Left, Right, Up, Right when the main menu appears.

Monochrome graphics:
Hold Select and press Right(4), Up(4), Down, Right, Up, Down, Right, Up, Left when the main menu appears.

Wider turns:
Hold Circle and press Down(2), Left, Down(3), Left, Down, Up, Down, Right, Left, Right, Left, Up when the main menu appears.

Transparent car:
Hold Start and press Up(2), Right, Left, Down, Down, Left, Up, Right(2), Up, Down, Left(2), Down when the main menu appears.

Big tracks:
Hold X + Select and press Right, Down, Left, Up, Right, Down, Left, Up, Down, Right, Up, Left, Down, Right, Up when the main menu appears.

Decrease gravity:
Hold Circle + Start press Right, Up, Down, Left, Right, Up, Down, Left, Right, Up, Down, Left, Right, Up, Left when the main menu appears

Bonus tracks:
Finish in first place on all levels in "STC" mode to unlock the HKS-VEC, ING-CAL and AUT-318 tracks. Finish in first place on all levels in "SSS" mode to unlock the TCY-TMR, KGS-ERS tracks.

Bonus cars:
Complete one of the following goals to unlock the corresponding bonus cars:
Finish in first place in the end of year championship race in each of the three levels under "NC" mode to unlock nine bonus cars (three per level).
Finish in second or third place in the end of year championship race in each of the three levels under "NC" mode to unlock six bonus cars (two per level).
Finish in fourth, fifth, or sixth place in the end of year championship race in each of the three levels under "NC" mode to unlock three bonus cars (one per level).
Finish in first place overall in each of the three levels under "TC" mode to unlock nine bonus cars (three per level).
Finish in second or third place overall in each of the three levels under "TC" mode to unlock six bonus cars (two per level).
Finish in fourth, fifth, or sixth place overall in each of the three levels under "TC" mode to unlock three bonus cars (one per level).