Solved

Is it possible to not run a race?

I've mathematically won the championship and I would save my engines for the next season. So I would not run the final races, or, if is it possibile, run with only one car. Can someone help?

you don't have to swap your engines just leave them run on old engines for the rest of the season

You can refrain from replacing the engines in your cars and also the parts.

tnx guys, I will try so