I've been playing GTS, AC, ACC, PC2 and PC3 back to back(Forza 7 is on a different tv). Same cars and tracks.
PD need to add connectivity to the road. The sensation I feel, is that the cars in GT are on 205 width tyres, while all the other cars are on proper width tyres. The car physics(dive, squat, suspension/roll) are fine. This goes beyond controller/wheel settings. There's a disconnect, in the details, with the road to tyre. Also, with the sensation of engine braking or lack of it. Maybe step up the wind resistance?
Anyway, I tested a race car, but PD have modelled a different feeling to high sidewall tyres on classic cars compared to low profile tyres on modern cars.
I'm not comparing this game does this better or ranking these games(if anything, I didn't believe it until I did them back to back, GTS and ACC are pretty damn close in terms of ease of play on controller). No negativity about that here. This is about the movement of the car. What we "feel" when driving it around. I'm not feeling the weight of the car or what it's doing underneath me, until it's probably too late. So to speak.
I honestly, now, don't think the GT physics will change. It's too easy for everyone. As in, the casual(majority) players really don't need to feel much more than the car turns when you steer it and the car brakes when you pull the trigger. It has to be. Especially, for players that never driven a car. I wonder how GT-GT4 would feel, using the DS4.
If PD want to go ahead and add more feeling with car behavior, I'm all for it. Is that what "Simulation Mode" could be about? More feeling? I don't know. However... Yeah, I'm convinced PD won't go any further than what is programmed in GT Sport.