As GT6 has my car in it, I compared it to mine, back when I had my ps3 and a wheel, to see how it behaved compared to my real car.
It handled completely different. I think PD just need to start from scratch with physics for their next game, rather than try to see what GT6 does wrong. It's ok for a racing game, but considering it's marketed as a simulator, that puts it up against far more realistic games.
In the game, my car handled like a fwd all the time. The tyres behave like they're made out of solid rubber, with no movement whatsoever. Grip is an on/off switch, you either have it or you don't, there's no transition at all, which I guess is due to the lack of tyre flex or pressure modelling. Tyres behave the same, whether cold or warmed up, and when overheated will return to normal instantly after the load is removed from them.
The suspension seems ok, but tuning is completely wrong for it. Spring rates and damper tuning makes little difference to the car's handling, and the geometry tuning is so wrong it's almost pointless to even have it in the game. Leaving it all stock, to compare to my real car, it behaves ok as a game, but not at all like my real car.
The transmission tuning seems fine, however the aero model is way off, making cars significantly faster than irl, and once you bring adjustable wings into it, I've found max front wing and minimum rear is the best on everything, which obviously is no good.
My car is awd, with a similar system to an Evo Lancer or Wrx Impreza. The awd cars in GT6 are all very wrong. All seem to have a fixed torque split, which, when standard, is wrong on every car I've checked. My car has a torsen LSD in the rear, open front diff, and Viscous centre diff. In game it behaves like a fwd, so I can't tell if they put a rear lsd in as standard, but the centre diff is locked to a fixed torque split.
My car, when pushed hard into a corner, will understeer initially, and due to the tendency of viscous diffs to be slow to lock, there's a noticable pause before the rear end comes into play, at which point the car rotates very well. This forces a very specific driving style to drive the car fast. You need to enter the corner close to the limit, but not too hard, then punch it before apex to force the torque to the rear, which will kill the understeer and the car rotates and goes through the corner with a nice neutral balance. In GT6, it understeers into the corner, and the only way to stop the understeer is to lift off the throttle and stay off it until you're going very slowly. Using any throttle at all will increase the understeer. The more throttle, the more the car understeers. No action from the centre diff. Car just behaves like a fwd.
I've also notied, when you put a customisable centre diff in the car, you can change the torque split from 50/50 front/rear, to 0/100 front/rear. This is impossible irl, due to the configuration of the car's drivetrain. If you could adjust the centre diff in my car, you'd have between 100/0 front/rear, and 50/50 front/rear. In game it works like a GTR. Drive goes to the rear, unless you adjust the diff to send some to the front. My car doesn't work like that, it's the opposite.
I've also noticed electronically controlled centre diffs, like the Attessa E-TS in the GTRs, don't work properly. It always acts as a fixed torque split, and not a variable one.
I honestly think it would be quicker and easier to list the things that do work instead of those that don't. Just my 2c. I'd like to see them build a new engine from scratch for GT7, as the ps3 one is just too flawed imo. They've got a lot of work to do to hope to compete with the realism their competitors are achieving.
.
👍
10th fastest person on the track that week, and I never even raced before. 
I have to add though, and I have stated it in an earlier post, that GT does an excellent job with modelling oversteer. My 328i and the kart I raced both feel identical to my G27 when countersteering.
