Something wrong in physics? Why in hard brake / when lift throttle / fast corners, terrible oversteer occurs? In WTCC 2015 this not happens.
Yes it does according to the drivers, tip for driving front wheel drive cars, don't lift off the throttle, keep some gas flowing whilst braking, only takes a couple laps to get the hang of and once you do your times will drop!
There’s nothing wrong with the physics. What you describe is called „lift off oversteer“. https://en.m.wikipedia.org/wiki/Lift-off_oversteer Since the update of the WTCC series physics (I think it was sometime last year?!), this behavior became very intense. The cars tail is now more unstable under braking and the cars are a lot more difficult to drive on the edge. I don’t know if S3 hasn’t updated the 2015 WTCC cars, but better stick to the 2016 cars, they behave more like the real ones with this kind of physic.