If you are modelling the filling of the carts in the warehouse and the delivery in the factory, then keep in mind that the number of containers handled in the reports will be twice the max number of containers on the cart. Sometimes people have a max tugger volume of 30 and see 30 containers in the report QTY field but are surprised when their utilization charts show 50%.
The volume utilization tab considers the PEAK tugger volume. As previously mentioned, a typical routing report will consider the container twice (i.e. pickup and delivery if you are modelling both). Now you need to consider pickup and delivery sequence. For example, during my delivery, if I also pickup empties, then there may be times were I pick up empties first and then deliver (so my peak would be greater than the number of containers I am delivering). There may also be times where the peak equals either the max of containers I am delivering or the Max I am picking up.