A few tips
When starting the game, do the Gran Turismo 3 trick (if you dont it wont work) then buy a nissan skyline as your first car. Gain a bit of money in the beginner races, then soup it up. Mine has 670 HP and is my second best car (my best is my 907 HP cadillac cien 02) and give the nissan dirt and snow tires. If your a good driver, you should be able to clear all the special condition races with the nissan alone.
We have more cheats and tips for this game here, Gran Turismo 4 cheats
Comments for this hint