The racing world is tough and deadly. Fortunately, you don't need to be tough just to enjoy it. You can do that with the model cars. You don't have to be a kid to play those as anyone with a knack to race wants to play it.
There are two challenges in each level and you can only unlock the next level if you can conquer both challenges. Each challenge will earn you money at the end. Of course, you need to have a better time or position to get some money from the challenges. You can upgrade your car with the money.