I think Beamng.Drive is very realistic and looks very good too. One thing I believe can help is if car damage particles and/or broken glass particles could have a longer lifetime and maybe collide with the ground. As of now it seems that particles just fall through the ground and that's it. One game that shows great looking graphics for car damage simulation is "Next Car Game." As you can see below the car leaves a longer trail of particles making the crash seem more devastating. Remember: This is just an idea and doesn't need to be implemented. I think it might be a good idea to make the particles able to collide with the ground and make it where users can set the maximum amount of particles and the lifetime of them.
I dont know how they would make the particles collide with stuff unless they had their own jbeam or other complicated stuff. As of now its just a sprite that appears when it hits or breaks. kinda like the smoke. No, exactly like the smoke lol.
I don't think the particles need to collide with other vehicles, I just think they should be able to impact the ground and stay there longer. That or get bigger particles as the current ones are a tad small (just ideas)