chaser_fan you bring up some excellent suggestions. However I feel some of them will require just too much processing power to do on the aging PS2, and may have to wait for the PS3 and GT5. Those things that you have mentioned are in fact very doable, EA/ISI have successfully modelled drying track surfaces, track/ambient temperatures, etc... But it comes at a cost, you need a very fast PC to run their F1 Challenge game, same goes for Sierra/Papyrus' NASCAR series of games. They even incorporate the build up of debris on your windscreen and wind velocity/direction.
Actually come to think of it, ISI have done mechanical failures quite well too, brakes can overheat, engine can overheat, you can run out of fuel, etc... But so has Papyrus, it just comes at a cost of high CPU power being needed, something the PS2 probably can't handle.
I bet, given the proper platform *PS3* PD could do all these things extremely well, probably even better than those companies mentioned have, it's just that right now, on the PS2, they have probably found their limit, but time will always tell
