I was reading a post on modding and the effects of different terrain and I realized that no one had ever mentioned this particular question.
Because no one HAS mentioned it I would guess that there is no difference but I will ask it anyway.
Does it matter how many wheeled vehicles are in a stack (Art, Supply Wagons, ect)?
What I am trying to say is if 1 Art slows you down a certain amount will 1 art AND 1 supply slow you down more OR is it that the penalty is a one time hit no matter how many artillery and Supply sources you have?