Instructions
Insert the "NASCAR Thunder 2003" game disc in your Xbox console and start the system.
Press "Start" at the opening screen. Scroll down and select "Settings." Press "A."
Select "Gameplay" and press "A."
Select "Difficulty" and press the right direction on the directional pad to change it to "Veteran" or "Legend."
Press "B" to save the settings and back out to the main menu.
Scroll down and select "Quick Race." Press "A."
Select the driver whose paint scheme you wish to unlock and press "A."
Select any track that you wish to race on and press "A."
Win the race (first place) to unlock the selected driver's paint scheme. Repeat with different drivers to unlock each paint scheme.