The HP limits mentioned earlier could be used with some success if changed to a bhp/tonne limit. This way your monster powered 2 tonne Vantage could tackle your tuned but ultimately comparatively gutless Elise.
This would allow better difficulty levels for things like the FR cup where car choice is wide and varied, the only problem is in events like the DTM cup where you can't easily tune down your car. It's these races where the cars are near identical where the AI is crying out for improvement. Not merely in raw pace either, but in their race craft (pit timing, don't get me started), passing and risk taking and collision avoidance.
I'm not sure the physics engine could be changed significantly. When your brain is trying to figure out what's happening with just your sense of sight, looking at the screen, it's hard to compare this to a real racer, where, sight, sounds, feel, movement, vibrations, and forces on the car all help you to determine how to control a slide, or feather the throttle. GT does very well with the limitations of your CRT box in the corner with the game boxes on it. Also for that matter the limitations of the DS2, which I would imagine 90% of the world or more plays their GT on.
Some people may be looking for the wrong things when looking at future GT's. I play this game as a toy, just for fun. For an hour or so of an evening to chill out after work. So is it more important to make GT fun with huge bodykits and exhausts and such which are being championed by many posts I've seen. But given the context of GT I still believe that the fun should be derived from the realism, and the satisfaction of having to wring every last drop of performance from your S2000 to catch that 350Z, then knowing that it was you that made the difference. You took an inferior machine and made it better just by being the one higher quality component in it.
It transfers to life, I take my bike to trackdays. I'm nothing special, intermediate group, moderate pace on a road bike and road tyres. Quite respectable I think. Although there is no official racing on thse days, people pass each other, and when you finally track down that 998R you've been gaining on for 3 laps and power around the outside of him on the exit of an off camber bumpy downhill left... For those few moments you feel like you are the greatest...
until the 12 year old on the 125 with slicks nails you into the next corner. Dang.
That's how I want GT to feel.
I write a lot when I get going don't I?
Kurtis.