I don't like the physics in the Geoff Crammond games. They seem too arcadey, with canned crash behaviour and the like, rather than "real-world" physics calculations. After I played GPL yeeeears back and got heavily into it, I couldn't drive GP2 anymore. Tried and hated GP3, and didn't bother with GP4. I had EAs F12002, which was cool, but I was at uni and off the internet at the time, so fell out of contact with the modding community and lost interest.
The CDTP and FSOne mods, and the built in BMW Sabuer in rFactor are the best out there at the moment for modern F1 on a PC.