On a few tracks, community-made, but it used to happen at Brianza, I have seen and been hit by AI cars shaking violently and surging forward. Haven't seen that at Brianza recently, but it happens on Ring Tourist and at least another track for me. I think I was using the Corvette every time. I'd just like to have your stories to see what's going on.
Does reducing the # of AI cause it to happen less or stop it happening, if so have you checked to see if the 'purple physics bar' (CTRL+C by default) is going full right when this happens?
You could also try disabling replays to see if that helps. Sounds like a hardware limitation like others have mentioned. (I read the title as "AI cars twerking". Dammit I hate miley )