Someone a while back (two to three years ago) made a port of the airport section/area of GTA IV liberty city. It was only the airport and whatever LOD models of the city were visible around it. It wasn't the largest section of the map for sure, just the airport and some of the immediate vicinity like the highway and such. I don't even remember if it had AI, but someone ported a section of it into this game. It was pretty nice but you also must understand that it takes a lot of work customizing the collision meshes so they do not munch on vehicles, especially curbs, fences, guide rails, some building details, light posts/signs, and the like. The collision system for BeamNG runs at 2000hz (hz = times per second), the collision system for GTA V (not IV, V) runs at 20hz, so by comparison, Beamng runs 100x more computation cycles per second, on many many times more node/beam points than GTA V - and GTA IV was simpler / less advanced than V obviously. So basically, what I am saying here, is it can be a lot more than just 'drag and drop a model from one game to the other, and add textures / texture entry scripts in'. I am sure you can find the old map from 2017~2018 or so around on this forum somewhere. I think it was Liberty City Airport or something like that. I might even have it on an old drive somewhere, or on the old computer in a mods folder, but I can't promise anything.