I tried this and it didn't go so well. But I didn't do the collision model and the high poly car model kept eating my car when I collided (probably front facing normals or over-detailed model) My advice would be to import it into Blender, then make a simplified version for the collisions, then export (making sure to follow Beamng's very specific file structure) as a .dae. Should work, but the textures will be a pain, as you'll likely have to manually sort them out.