In the first horizon your car had to be a certain class to race in the races. Is that the same with horizon 2 or can you upgrade your car as much as you want to and you can still use it in the race?
The field of opponents is matched to your chosen car’s PI, so the only restriction is the car type. In the Xbox One version at least, you can choose which car type championship you want to race (after some initial progress) each time, so you could keep racing in the same car in whatever upgraded configuration you choose.