Full pause screen

Pause the game and press X + Y.
Unlock courses

At the options screen, hold X + Y, then choose the Passwords selection. Enter one of the following case-sensitive passwords to unlock an additional course
Enter CinqueValvole to unlock the Fiorano course.
Enter LiebeFrauMilch to unlock the Nurburgring course.
Enter Stars&Stripes to unlock the Laguna-Seca course.
Enter KualaLumpur to unlock the Sepang course.
Enter DaysofThunder to unlock the Atlanta course.