The AI on GT5 is miles better than that of Forza 4; I've played both. Mainly because the AI in Forza strictly sticks to the racing line. It doesn't matter if somebody swerves in front of them, or a big collision happens right in front of them; they keep truckin' right into the mess. I found that I was getting pit maneuvered unintentionally because the AI did not know to get out of the way, or form a new racing line. And, the AI intentionally sabotage themselves. In several races, I saw AI drivers not even bother to brake for a corner, and go careening into the grass. Even if I restarted and did the race again, the same exact thing would happen. And that's no fun; it means that everything that the Forza AI does is pre-planned, or scripted. In GT, if you restart a race several times and do it, you get different outcomes each time, but in Forza, it's always the same. That's what's wrong with the Forza AI: it's all artificial. But then again, AI is artificial, but at least in GT, it doesn't always seem like it.