A race track is where all the race car meet. There, you will need to prove that you are the best and beat all your opponents if possible. But, in any case, you can't do that, getting a good position in the race would do. You will get some reward money from the race.
This game is all about racing. The idea is simple as you just need to beat the other participants in the race. But, if that is not possible then getting a third position will do because that will unlock a new level for you. If you want a new car then you should aim for the first position as that is the only way that you will unlock a new car.