Unlock all drag tracks:
At the main menu, press Left, X, Right, R, X, L, White, Black. 

Unlock all drift tracks:
At the main menu, press Right, Right, Right, Right, Left, Black, R, White. 

Unlock all sprint tracks:
At the main menu, press Up, Black, Black, Black, R, Down, Down, Down. 

Drift physics:
At the main menu, press R, Up, Up, Up, Down, Down, Down, L. 

Unlimited turbo:
At the main menu, press A, B, Y, Y, A, A, B. 

Unlock all circuit tracks:
At the main menu, press Down, R, R, R, Black, Black, Black, X.

Easy style points:
After you unlock the oval drift track, go into "Quick Race" and choose that track. 
Then, race around it using the handbrake to powerslide into the corners. 
Depending on how good you are, you will unlock rewards every time you fill your 
meter, which does not take too long.

Go to quick race mode and choose any circuit. Set it to five laps with maximum 
cars on. Then, just get near misses in a row to get a large amount of points. Once 
your reputation goes up you can make 20,000 points in one go around.

Use rims that normally will not fit: 
Certain cars can only fit so big of a rim. For example, the Miata can only fit 17s, 
but if you get a car like the Skyline put 20s on it and trade it in for the Miata. The 
Miata will now have the 20s that the Skyline had in it. Do not try to install any 
other rims on your new car because the rims will go back to the maximum sized 
allowed. 

Shoot smoke from nitrous:
To make nitrous shoot out smoke, put your car in neutral, or at the beginning of 
the race press Nitrous.