Go to Fight to the Top Mode, to My Nascar, then to Edit Driver and enter:

First name: The
Last name: Intimidator
Unlocks Dale Earnhardt

First Name: Open
Last Name: Sesame
Unlocks All Thunder Plates

First Name: Walmart
Last Name: NASCAR
Gives you 10 million $ in Fight to the Top Mode

First Name: Walmart
Last Name: Exclusive
Unlocks the Lakeshore Drive Track