In some of the older gMotor games I remember they have a few slider where they can tune the contribution of engine vib, brake, curb...etc to you FFB input. I feel like that was the easiest to understand the tune. This is very heavily on the physics side and makes it just hard to understand and adjust without going through all the documentation. Eventually if you are really bothered by it(like I was) you will go through the trouble but its just not something I think a gamer should need to go through to enjoy the game fully.
BTW on the AI front:
I wasn't anywhere near this when the pile up there happened....
Older game does this too, but in a lot of those they have the courtesy of resetting the cars back to the pit. This just basically stops a session...