Win all races in C3 career mode to unlock Custom Corvette mode.
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. Note: This will only work when you race one on one.
After you have unlocked the 2003 Z06 choose the manual transmission and you can drive the car to 7000 RPM's.
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.
Win all C5 career mode races to unlock the Route 66 Challenge.
Go to the options menu, go to "Change Name", and enter "XOPENSEZ" as a name.
At the title screen, hold L + R and press Up, Left, Down, Right, Left, Right, Left, Right to unlock all bonuses. If you entered code correctly, the word "Yeah!" will be spoken.