You mean Levels of Detail (LOD's). Unfortunately, most of the performance usage is from the physics skeleton, not the visual mesh. And changing out either to a simpler one in realtime is probably not possible with Beam.
Re: AI mode I would like to see a race mode and demolition derby mode for the AI so people can have legit races and demolition derbys on the game
That could be possible. We don't know, maybe the devs have a system coming where at distance the physics skeleton sort of disappears and when you get to a specific range it comes back again much like how other LOD's work except with the physics instead of just the visual stuff. It might be harder to implement but that is just one of the many reasons this game is going to take a long time to finish. They want a sort of free roam open world thing with a decent population of npcs, and to do it they are going to have to figure something out to solve this issue.
I have a PC capable of running the game fine on full settings, and I set it all on full settings and spawned fifteen cars without lag, but as soon as I pressed forwards,the game broke.
^Specs please. I dont think thats possible, unless you just so happen to have an 18 core, 36 thread Xeon, which, AFAIK, is the only cpu capable of doing that.