The failure to completely mechanize the Wermacht was a huge failure.
Interestingly our Navy had trouble supplying the fleet with fuel in the early part of the war as well. Battles and ship movements were tied to fuel supply.
Point taken.
Even when the Germans turned east to Russia they counted too much on using the Soviet rail network which was a different gauge than used in Europe.
One of the mistakes of the Japanese at Pearl Harbor, other than missing our carriers, was failing to destroy the fuel tanks. They left all that fuel sitting there available to our navy when taking it out would have cost them nothing.