In overtaking course (training mode) if we touch a car, we couldn't complete the stage. But in a single player race when AI cars cause a collision, they go on without any penalty. Of course there is a huge difference between touching and crashes.
AI cars should be penalized such as stop-go or drive through pitlane penalties according to collision results.
In addition to this I've picked up some AI car faults in an SPR file:
http://www.megaupload.com/?d=WHBSYIJ8
First of all, AI cars have a linear pitstopping behaviour. All of AI cars go to pitstop on 12th lap. While AI1 repairing at pitbox, AI2 crashes to AI1 straightly as of 14:10. There are no direction change and avoiding crash effort of AI2.
This sweeping fault causes clutch overheating and damaging AI2. Despite the damage, AI2 tries to go on racing and halts on raceline very dangerously (on Lap 13).
For race safety, hardly damaged AI cars should be retired and park safely (far from raceline).
Additionally, a weird AI fault occurs after race finish (on Lap 21 - 23:50 and 23:57). AI3 and AI1 don't obey yellow flags and bump into AI2 and AI3 respectively. However AI3 and AI1 was racing properly and avoiding an AI2 crash before the race finish (Lap 15 - Lap 20 period).