To make traffic look better, BeamNG could draw flat sprites of cars in the distance moving along the roads. This would really make traffic more immersive as the roads look more busy. And since those aren't real cars, it shouldn't affect the games performance. Optionally If you get close to those sprites they will transform into actual cars. I'm not sure if that will work well cause some of those sprites when transformed would go above the maximum number of real cars allowed in traffic.
It would probably be possible to animate some sprites or physicsless low poly meshes in the distance, the difficulty here would be synchronising the low poly version with an actual one, to get the density right you kind of have to predict where the player is actually going to drive.
Yeah that's the main issue. But i guess it wont be that bad if some of those sprites would just disappear without being replaced by real cars.
I like this concept. One of the reasons why BeamNG traffic AI kinda doesn't work is because you either see cars spawn in front of you or when they dont you have 30 miles of nothingness ahead.