So basically to this date, you drive a car into the water it will just sink. But like Real life cars you drive into water they will float, from the air pressure inside the car, until they slowly fill up with water and sink. I think it would be a great thing to add to the SIM to give it that more bit of reality. The cars need that buoyancy. Example:
I don't know anything about physics or coding, but I think it does exist ingame, though to a limited extent. The water seems to act like a wave of nodes. I think if it were easily possible to make it to where the water has collision with the exterior (Which AFAIK, hasn't been done in a game before) then this would exist.
I feel like they need to touch up the water before doing this, Right now if you go through a puddle or stream you can see it through the car just like grass bushes etc, But they would need to implement a boundary around the cab to make the water go around the cab instead of right through, Than they would have to work on trying to make the water more interactive with the vehicles which could Maybe put more Heavy frames on some maps and for the slower computer users they will have another thing to worry about, All i'm saying is There is a lot to work on before just something that simple can be performed into the game.
they'd either need to make water that actually flows, or just fake it with a fixed rate, like they do with engine flooding one of these things is less unlikely than the other, and probably could just be implemented by a user script
There is kind of an interaction between cars and water, i found that out by driving a drag pigdon into the water at gridmap and it flew
Such a simulation would have to consider if car's windows are broken or not, same thing with a convertible VS an hard top car.
There's already buoyancy in BeamNG. If you use larger tires and over-inflate them you sink slower. some big tire mod sometimes pervent you from sinking.