Ditto on several points.
The Germans hoped for a quick war and got it, but lost their minds when they whipped Poland, Benelux, France and decided to go take a whack at Russia from the west which has been a miserable failure.
They had issues long before the first panzer rolled on Poland as mentioned before- the insane balkanization of effort and multiplicity of designs to support vs picking a few useful truck/jeep, half-track designs and making enough to have a positive impact.
Sure, there were some white-elephant projects that devoured and diverted valuable resources- the commerce-raider cruisers, the V-weapons, and the Final Solution that were crucial to advancing and improving the logistical situation on the Eastern Front.
What escapes many in discussing more motors is the fuel to fuel them. Anyone have any idea what the output of Ploesti and synfuels plants was and how well they could have supplied more of these proposed trucks and AFV's?
Maybe the Heer found themselves using millions of hayburners b/c there was hardly enough fuel for panzers, much less support vehicles?
Also, roads in the Soviet Union were horrible and the Wehrmacht had major issues staying supplied when they had to get away from railheads.
Horses could navigate the rasputitsa. Jeeps had trouble and tanks sank in the mud.