Enter the following at the title screen.
Code: Hold L + R and press Up, Left, Down, Right, Left, Right, Left, Right
Every car and course
Go to the options menu, go to "Change Name", and enter the following.
Custom corvette mode
Win all C3 career mode races.
Route 66 Challenge
Win all C5 career mode races.
Never lose a race
When losing a race or getting into to a wreck, press Start. Select "Restart Race" and the race will begin again, not be count against you.
Get cops off your tail
When a cop starts to chase you, try to speed as much as possible or take a shortcut. With the 1978 Corvette 25th Anniversary, the cops will catch up with you -- try your best to get away from. REMEMBER: this will only work when you race one on one.