It matters to what you like best in a racing game
The best part of this game is the amount of cars and graphics on the cars. If you would like a game based on the cars, you got the right one
Here are some hints on to unlock different cars:
Mazda rz8 -------------------- Complete 75% of the races
f094/s ------------------------- complete all of the races
f688/s -------------------------Cmplete simulation mode
f686/m ------------------------- complete proffesional league
f094/h --------------------------- Complete endurance league