someone made a website to help with setups
obviously you need to input 2 different setups before it can try and work out what you should try.
put your actual setup on the left side, then click under each item on the right side and select optimal, bad or whatever.
once you have 2 setups stored on their hitting Find Nearest seems to give good suggestions
I got 100% on driver 1 and 97% on driver 2.
weirdly it ran out of setup options for driver 2 and couldn't find me a 100% but I guess it got close enough and way better than randomly choosing stuff your own each time.
car setup in this game is annoying as hell and looking at it all that it determines is how many bonus attribute points the drivers get anyway so I doubt the setup in reality makes any different outside of the bonus points awarded.
seems the only point of car setup is to be some stupid minigame that can give you at most about 15 attributes point buff spread across control , accuracy cornering, breaking and reactions
so even a fairly poor setup will likely be minimal difference in actual performance.
it probably counts towards the exp your drivers get though.
but shows any bizarre design choice they went with that seems only to keep the "simulation" fairly basic
oddly enough I don't think anyone has picked up on it yet as being an issue
TLDR car setup doesn't actually change the performance of your car it only amplifies your drivers abilities.
The only thing that effects your cars actual performance are the stats of each car part, setup is irrelevant so there's no setting a car up for a wet race etc