But couldn't you draw the conclusion that an acknowledged inability to provide fuel (oil) encouraged a lower level of vehicle production.
In other words Germany was not a fully mobile force because it did not have the capacity to fuel a fully mobile force and therefore it concentrated on alternatives such as horse drawn units in order to have enough fuel for the motorised units it had as a result even capturing more oil would not necessarily have helped because it did not have the vehicle production capacity to utilise it anyway.
Basically they got themselves into a catch 22 situation.
I think it is an interesting topic but I am not sure it is a quantifiable one.
Certainly for at least the 1st 1/2 of the war that would be a very difficult question to answer. I do think that as they fought into 44 they were pinched for oil.