Hint - Drag Race Bet Exploit

When you have enough money ($10,000 is a good amount to start with) host your own event and make it a sprint. Allow only class one cars.

This leads to either a corvette or a viper being the competitors. Always always choose to bet on the viper as it is much faster than the corvette. If both drivers have the same car look for which car has the higher BHP. If they are identical or there is only one car, refrain from betting.

Unlockable: Arcade Mode Cars and Tracks

Go to the Extras menu, then the Cheats menu, and enter PIES.