From what Dave posted earlier about the idea of varying temperatures around a track, and I guess that will include varying grip levels throughout the day for instance and varying grip at different parts of a track.
I am really looking forward to that aspect more so than anything else, i couldnt care less about improved gfx etc or even AI.
On games I have rarley raced the AI, only once or twice on F1C, though quite a few short races in gp4. But mainly I prefer to test.
"Trulli was slowing down like he wanted to have a picnic" LOL