Well, I did some tests with the Hungary magic file (desc 65):
80 ; some chance. same chance multiplied with race perc.
I changed this to a value of 0 and wow, no more stupid AI mistakes!
I did a few all-CC races and the only runners to retire had mechanical problems, whereas before at least 4-5 would retire due to spinning out and crashing against the barrier etc. This is great news! Now we can set realistic values, certainly much lower than 80, probably 15 or 20 is realistic.