Is there some sort of plugin or mod that allows mods from your downloaded folder to be spawned as AI traffic? I'm assuming the answer is no because I can't find any documentation on this anywhere but if someone knows a way please let me know!
Some cars mods will spawn as AI (etc Gavril Vertex), but the easiest way is to spawn the cars you want, then tab back to your vehicle, then in the radial menu, click AI, then traffic, then start traffic.
There is a setting in the "Gameplay" options tab on the left of the screen. Under the traffic section, enable "Allow mods to spawn". I think this is the answer to what you are asking. @charge_1 has a solution too, which would be better if you want to be specific with which vehicles you want spawned in. Something to note though is that if you spawn in cars, then start the traffic, the traffic vehicles are the regular vehicles, not the "simple traffic" ones (simple traffic vehicles only apply to BeamNG vehicles, not mods), so you might experience worse performance (I think).
This is a great idea! thanks --- Post updated --- Good to know, My computer SHOULD be able to run it but I will keep performance in mind, thank you!