Select Earn Your Stripes mode. Then, enter one of the following case-sensitive first and last names at the driver information screen to activate the corresponding cheat function:
All cars in Chase mode
Enter "Checkered" as a first name and "Flag" as a last name to unlock all cars in Chase mode.
All fantasy drivers
Enter "Race" as a first name and "ThePack" as a last name to unlock all fantasy drivers.
EA Sports car
Enter "EASports" as a first name and "Car" as a last name to unlock the EA Sports car.
Wal-Mart track and car
Enter "Walmart" as a first name and "EveryDay" as a last name to unlock the Wal-Mart track and car.
Easy pole position for Daytona and Talladega
When qualifying for a Daytona or Talladega race, turn off braking assists. This will allow your car to reach maximum speed, resulting in a pole position every time. This works in all race modes.
Easy Gold in "Follow The Leader" challenge
Select the Gold (Hard) challenge for Follow The Leader. When the race starts, find the best spot to ram your car into the wall (head-on works best). You have to hit hard enough to destroy the suspension or you will get a "Failed" message, saying you hit the wall too much. If done correctly, you will pass the challenge. -From: Tribal
There's an Infield part on Nazareth Speedway (without the pits) you can drive in. Go in there, and you'll start pulling away!! You'll also get some impossible lap times. This works in ALL modes. Just enter the infield and smoke the competition. My best lap was 25.59 secs.