One of the major problems with the Great War, and why it suddenly ended up in a stalemate where millions of men died for the gain of a single mile in static and brutal trench warfare, was because, to put it simply, military weaponry advanced well beyond the means of transportation.
Trucks and armored vehicles weren't really a thing yet. Those were inventions that spawned from the end of the Great War and throughout the interwar period. Hell, the entire oil industry was really not developed enough to sustain a full-scale motorized form of warfare.
And though Bruno had begun making substantial investments in the oil and natural gas industries, if he was being honest, it would be years before Germany had enough fuel stored to properly make use of such advancements in military transportation.