Turn auto-save off.
Go to the races in career mode.
Then host a sprint race for Class 1 cars.
In the race there will be a Dodge Viper and a Chevrolet Corvette.
Bet all your money on the Dodge as it is much faster than the Chevrolet.
(If there are 2 Doge Vipers don't bet at all)
Then when the sprint ends collect all your hard-earned cash.
NOTE: The Dodge doesn't win all the time and you'll lose all your bet money,because the dodge sometimes spins out of control and loses.
To avoid that just turn auto-save off.
When you lose just turn the game off(press "Home" button) and then turn it on again.
And if you had auto-save off, you'll have all your money back
In order to never lose a car because of a lost pink slip race, turn off the auto save feature and whenever you lose a pink slip race go back to the start menu and you will have your car again and it will be like the race never happened
Get 100% in career mode to unlock the extreme nitrous series in arcade mode.
To unlock all Arcade Mode cars and tracks go to the Extras menu and select the cheats menu and type "PIES" (without quote), this will Unlocks all Arcade Mode cars and tracks.