They say that only those, who belong to a rich family can become a racer because only they can afford those racing cars. Besides that, those upgrades aren't cheap, as well. If you are not going to invest then don't expect to win. Of course, you need to practice a lot, but without some capital to fund your interest, you might, as well forget about it.
Drive your car as fast as possible till you reach the finish line three times. Maneuver your car on those curvy road and try to stay on the road all the time to keep your current speed. Watch out for those oil sleek because you would run out of control if you manage to drive over it.