NASCAR Thunder 2003 Cheats

To unlock all of the fantasy drivers available in the game, create a new character/car and put your name as "Extra Drivers" (where Extra is your first name and Drivers is your last). If you want to unlock Dale Earnhardt specifically, simply enter your name as "Dale Earnhardt" (where Dale is your first name and Earnhardt is your last).

NASCAR Thunder 2003 Unlockable: Richard Petty

To unlock Richard Petty, create a new car/character and name it/him Richard Petty.

NASCAR Thunder 2003 Unlock Tiburon Speedway
To unlock Tiburon Speedway, insert a memory card containing a save from another 2003 EA Sports game before turning on the PSX.