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 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.
Easy money
On empty race days, create a sprint race and enter it. When it starts, use all your nitro and just keep pressing L near the redline. You will usually win about 95% of the time.
On empty race days, host a Class 1 sprint race. Bet all your money on the Dodge Viper, which will usually always win. If there are two Vipers, do not make a bet.
Easy way to not lose cars
All you need to do is take out your memory stick before it autosaves on the menu that shows the pinkslip track that you are racing. After the race, if you win, just simply hit options menu, go to game, and put autosave back on.
Extreme nitrous series
To unlock the extreme nitrous series in arcade mode get 100% in career mode.
Unlock all Arcade Mode cars and tracks
Go to the Extras menu. Select the Cheats menu. Type the code PIES.