to be honest i am not confident about the multiplayer part yet because we have recently added and it feels a bit laggy at the moment. we built it on top of regular pawn replication + relaying inputs from server + client side interpolation. unreals pawn replication had problems with rotation updates at that moment so we had to use interpolation to make sure the transform is correct but it added an extra small delay. the physics interaction feels nice and natural between vehicles(at least at low ping) but we have not tried that kind of(putting on top of a large physical object) interaction yet. our focus will be on replication for the next release(after v1.2) and we also plan to put a multiplayer demo too.