I have many hours in the free play mode and I have noticed some particular behaviors of the AI.
First of all I would like to say that they are not affected by tire or fuel wear. So whatever tire you use, it will have no effect (with hard ones you should go slower than one with soft ones). This ruins the strategy.
I also noticed that the AI races with a standard set up. If you race with the nascar cars in the daytona oval you will notice that you will have a higher top speed only because you have lowered the aerodynamics. The AI instead has a fixed aerodynamics that limits their maximum speed.
The free play mode should be improved, it seems really abandoned. It lacks the race weekend with free plays and qualifications or the possibility to create your own custom championship. Is it so difficult?
I don’t know if I explained myself well, I hope I was helpful