The AI have had many improvements that mean they can get around in most vehicles on most tracks. They have an adaption system that deals with brake balance etc. (you may read the thread, it's long).
Previously they were very optimised for the LFS vehicles and not adaptable enough for mods. So it's possible that for some LFS vehicles, they are now slower, because of the small safety margins they must leave in order to not crash so many mods as they did before.
But...
1) Your thought of "scam bots" is totally against my philosophy of game production. I have no interest in giving AI extra grip or fake physics or whatever. One thing I learned is that I am nearly incapable of working on things that I'm not interested in, especially when the work is so intellectually demanding as coding. The AI in LFS use the same physics as the player.
2) This is not a good time for me to waste more time, trying to make AI faster in the old (current public) physics system. If you had followed the thread, you would know that I am trying to release this update as an official version, so I can finally work on the version of LFS we are all waiting for, which has new tyre physics and AI that is already adapted to that new physics. So as I keep saying, I'm not working on the speed of AI in the current public version, fake physics for AI (never will do that in my life) or any other physics changes. There were some slight physics changes done to make the bike handle better, but I'm sure I made it clear that's as far as I was going.
So... to summarize any relevant point, it is possible that official cars or some mods actually run slower, but as mentioned, the mods in general can actually stay on track instead of spinning off at any tricky corner.