One wartime publication suggested planting the wonder-crop that does everything:
Die Lustige Hanffibel. Loosely translated, that's "The Humorous Hemp Handbook." Apparently, hemp can be used to make biodiesel and ethanol. Here's the cover, complete with contented, smiling anthropomorphic Nazi
Cannabis sp. plants:
OTL Nazis on speed, ATL Nazis on weed... How about Nazis pressing on use of cannabis as less resource intensive than alcohol which could be used for vehicle fuel instead?
But to get on track, while all sorts of substitutes from Fischer-Tropsch to alcohol and wood chips existed, they were all mightily resource intensive. Even Finland switched off the wood chip fuel as soon as possible.
In addition on investing rail network instead of autobahn network I wonder if widescale electrification might have also made use of energy more efficient? For road network, how about trolley truck network?
(Picture below is from 1930's Sydney)
On warfare, how about more investment on artillery instead of tactical aviation and more investment on Flak instead of interceptors? On Flak, even most costly guns were dirt cheap, for example 12,8cm Flakzwilling 40 cost some 202000 RM contra one ME-109 about 85000RM. Life expectanct and most possibly kill ratio too was much more favorable for a Flakzwilling...
On cars and trucks in general, how about a program to construct electric cars and trucks in general, as they would reduce dependence on imported oil? These would not be useful in fighting, but would cut fuel consumption in the home front. Additional bonus would be battery industry capable of turning out more capable U-boats than historically.
https://en.wikipedia.org/wiki/Trolleytruck