It would be helpful if we had a (optional?) highlight of the different values for the settings in the garage, e.g. a different color or shade of gray if a setting is different from the previous setup selected, or even green for higher values, red for lower.. Or something like that.

Like for comparing setups? You would probably want to know the exact differences between the setups as well, the numerical values...

Yes, so first the highlighting would make the setup differences stand out, and second you'd just click from one setup to the other and more easily keep track of the target setting(s)..

Setup A and B are identical except for B having -.5deg camber on all wheels and +20kPa on the rear tires. So clicking on setup B from setup A would highlight camber (either the title or the value, or both) in red, and pressure in green, or whatever color scheme is best adapted.
Non numbers like LSD type would have a neutral highlight tint.

I wouldn't mind having the value difference relative to the previously selected setup, but I don't know if the devs would find that too cluttersome.

Meh, I think it's easy to see the differences in setups now, you just flick between the 2 and there you go

So you think this would be a net loss for LFS?