Speed is power when it comes in racing and this is applicable whatever race you join. That is why; most racers would upgrade their car the as soon as they got the money. If they are not going to do this then they wouldn't have a chance in the upcoming race.
In this game, speed is still necessary and you need to be on top of your game. Other than finishing the race with a top spot, you also need to do another task get some extra benefit which will be useful in future races. Of course, grab as much coins as you can get your hands unto.