Nothing can be more exciting than a race. Your a race car driver and you are enjoying it. Everyone knows that if you are enjoying something then that is the best job for you as you won't grow tired of it. A street race is illegal, but some people race in it since they can't race in a legal for whatever reason.
The idea here is to beat all the rest of the racers, but it is not a requirement as you can unlock new level even if you don't belong to the top three. If you manage to be in the top three then you can unlock a new car. You will get the reward money after the race and you can use it to upgrade your car.