The primary reason Germany was so reliant on horses for logistics isn't that they weren't able to build cars, but that they didn't have enough fuel. Germany was

The primary reason Germany was so reliant on horses for logistics isn't that they weren't able to build cars, but that they didn't have enough fuel. Germany was blockaded by sea and none of the land they had captured had significant oil reserves. Romania had some, but not enough to feed their tanks and airplanes. A lot of German fuel came from coal liquefaction. About 90% of Germany's aircraft fuel and about 50% of the diesel fuel came from coal liquefaction. Contrary to what Factorio would have you believe, coal liquefaction is an expensive process- so expensive that producing enough fuel to convert your logistics supply chain from trains and horses to trucks just wasn't in the cards for Nazi Germany. Through the lens of "Germany doesn't have enough fuel" a lot of Hitler's decision making makes a lot more sense. Lots of people talk about what would have happened if Hitler had tried to take Moscow instead of deciding to drive south towards Baku. The speculation goes that if Hitler had taken Moscow, they could have won. Well, no they couldn't: they didn't have enough oil to win the war. Baku is where all the oil is, so if Germany had been able to take Baku, it's possible that they'd be able to win. Well, they weren't able to take Baku, so they lost the war. It also explains North Africa; if the Axis were able to take Egypt, it would have been relatively easy to continue the drive on to the oil fields in the Middle East. (closing the Suez Canal would have effectively cut off the British colonies there)