That seems odd as I always thought the Germans' heavies were over taxed in the transmission and drive train areas and constantly needed repairing there. having to push an additional 30-40 tons should blow the sprockets off them :)
Also one would think the Soviet diesel should be more apt to develop power on demand than the petrol burners of the Germans.
Faith Divides Us, Death Unites Us.... "We were never to say die or surrender" -- Chard