The AI in pCARS is like playing in a public online server. And I'm saying that as a €100 backer.
They dive bomb from miles back, they cut the track by massive amounts to get past. They try to run you off the track in practice sessions, they don't give a monkey's you are on a hot lap when leaving the pits. The only thing they don't do is drive the wrong way around the track. They also don't lap at consistent times.
There can can be 4 seconds difference in their times between, practice, qualifying and races. It's not track evolution either, they can be quick, slow, quicker. Or any combination of the three.
They also take some corners dangerously slow and other corners impossibly fast. Some of their brake points are half of what you have to do in the same car. Even if your lap time is quicker than theirs.
And most of this was pointed out before the game was released.
Like I said, they AI in most racing current sims is very poor one way or another.