Finding a game

Good afternoon.

I want to hear from you which of the recent racing games is best suited to put together a custom and personal MOD. To play offline, really. In short, I want to create my own MOD, with the cars I choose, with the personalized paintings, in as much as I can.

I want to join GPGSL and GPGSL-3 carsets, totaling 40 cars.

Is there any game I can do this?

Thank you!