Regarding Pcars handling, I would put it somewhere between Shift2 and AC. I could not stand playing Shift2 - even with the zero dead-zone and other realism mods. That was truly like steering a boat to me. Grid was much better but, barely playable. Maybe it was the wheel or settings I tried but, I didn't have the same understanding of FFB setup that I do now. All I know is that I lost interest really quickly when the handling was not even close to being believable. Much of the car-handling in Pcars already surpasses that test. That is not to say that it is accurate to real-world physics, just that it is in that "gray area" between the two. I consider Dirt2/3 to fit into the lower-end of that category - not true to life, just believable enough handling to be fun.
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At this point, the end result is still all speculation in terms of how the handling will compare when complete. Seeing the amount of effort and dedication that is going into making Pcars does suggest that it will end up being very good. AC-level handling is a tall order in my view but, time will tell where it ends up and even then, the only thing guaranteed is that people's opinions will vary wildly - just as they do with every other title in development now.