Please explain what does the setting "Anti-Lock brakes" and "Traction control" in the settings Difficulty? After all, in the Setup of the car there is a separate setting "Anti-Lock brakes" and "Traction control". If I turn off, for example, "Anti-Lock brakes" (Off) in Difficulty, then in Setup - Electronics "Anti-Lock brakes" is available and configurable. And I can feel it on the FFB.
The ABS and TC in the Difficulty was the original way it does ABS and TC. It is more of an inexperienced racer driver aid. Some one who hasn't driven racing games before. The AC and TC works in all cars, but the car physics file might have lines to add weight as a penalty for running it. The ones in the car set up would equal what the car has in real life. So a GT3 car would have both while an Indycar has none.
Are these settings in different places independent of each other? Do they complement each other for GT3 car (add up)? It feels like they add up.
The rule of thumb is to use setup options in first hand. I *think* difficulty is using more or less the same algorithm for calculating ABS and TC. I don't think they add up as such, so for example if you use high on both, it wouldn't make sense for the sum to be some ultra high level as that would not benefit anything in lap time. The problem with difficulty is that many cars have weight penalty with aids, so for example when you set TC on with some open wheeler, you may end up with a car that is 5 kg heavier, for example. The weight penalty is never applied for setup options since those are legitimate aids.
I did so, turned off in Difficulty ABS & TC.. It's more fun to drive! Even with ABS=9 in Car Setup...