The physics weren't that bad for Shift 2. Of course, it was an arcade game, but it was not Burnout!!! It was meant to be a Forza/GT5 kind of game for PC. And above all, there were control filters for the usage of gamepads even if you were using a steering wheel, resulting in major lag in controls.
All that is gone in PCARS. And all the cars now have nothing to compare with Shift 2. The 1968 Lotus 49 F1 is a major pain to drive, for example, even compared to the earlier versions of it, when it had wings for more grip.
Really: please, try it before criticizing.