They will routinely drive off into the grass, especially when attempting overtaking. I had to give up on an AI race twice at Interlagos, because the first three corners become undrivable. I was using GT3s at around 93% strength, 85% aggression. Curitiba also had the problem the last time I checked. Feel free to post other tracks/corners with that problem, in this thread. Also, all the tracks start off with a huge amount of **** off of the racing line. I know of no series that would start a race before sweeping that up.
Isn't it great that dirt on the track happens? Even better if the AI actually makes it happen during the race.