Save your profile after eachrace. When you lose or get caught by the police, exit out to the main menu. You will be asked to save your profile. Select "No", then go back in to the game. You will have everything you had before the race.
Enable the Auskagel code to get $100,000. As your car, select the Ford Focus (car #5) and tune it until no more modifications are available. Next, race in class A against the best opponent. When racing and you are in fourth gear, start the NOS and go on the lane that your opponent is in. Then, either brake (if you are winning), crash into your opponent's side, or hit him from the back. If done correctly, you will see a huge explosion and both cars will be destroyed. It is only a $300 fine and your car will still be intact.
Wait for the girl to say "Go", then quickly shift up. As soon as you hit 7,000 on the RPM meter, shift up. From here, tap up to get boosts of speed until you get to 7,000 again. Note: On fourth gear, it will be very hard to get to 7,000.
Once you hear sound but do not see the cars on the loading screen finishes, press SPACE. It will look as if you are flying down the road towards the cars. Note: Doing this too many times will cause your game to glitch (both cars swerve near the finish line).