what is that core functionality in unreal physics, can you define it, I’m not aware of that.
I doubt that what you want and what you define as “core functionality” are not the same thing.
afaik there is no physics setting that can simulate a wheel in mud or sand.
if you want a wheel to have a drag effect then you can imitate the behavior somehow, gave you a hint earlier and it is pretty simple to implement. if you are not willing to do simple stuff then you’ll have hard time making games.