Some guy digitized the USSBS (US strategic bombing survey), as it's not available on the NARA site, nor on the US.his.mil - site.
http://www.ordersofbattle.darkscape.net ... bsoil.html
It contains quite a few tables/figures which display the German oil production/consumption during the war.
http://www.ordersofbattle.darkscape.net ... /fig23.gif
FIG. 23:
The monthly consumption of motor gasoline peaked in August 1944, amounting to around 200,000 metric tons, while the gasoline in stock dropped to around
240,000 tons the same month.
One reason here is that the Allied (mostly US) Air raids on Hydrogen plants - which started in March 1944 (iirc) had quite some impact, plus the Rumanian oil fields were contested/attacked by the Russians later on.
The loss of these oil fields left Germany with the output from the synthetic oil production (made from coal) and a tiny oil field in North Germany. The combined output here never exceeded 80,000 tons per month (often less).
The monthly production of gasoline dropped from 220,000 tons in March to around 75,000 tons in July 1944, and never exceeded 80,000 tons for the rest of the year.
It's a no-brainer that after the retreat through France and Belgium and after fending off Market Garden, the consumption decreased big time (August through November), as enormous amounts of vehicles had been lost in the course of these events.
Still, the OKW determined that around 4 million gallons should be allocated for Army group B for the operation "Wacht am Rhein" (
15,141,647.136 liters if i did my math correctly here = 15141.65 cubic meter). The daily POL consumption of Army Group B peaked at close to 2,000 cubic meters on 18th of December.
As you can see, fig 23 clearly shows that the overall consumption (all fronts) matched the amount of produced oil/synth oil in November, but started to exceed this amount in early December again, so the stock (POL reserve) had to be used in order to mount an offensive of this scope. Vehicles not vital for the offensive were emptied and gas stations all through germany had been searched for "idle" gasoline.
Most Civilian vehicles had been converted to woodgas powered vehicles by then, already.
On paper, the fuel assigned to the units participating in the offensive was sufficient, but a significant amount of fuel did not reach the Korps depots in time, due to the transport drama and to the fact that the fuel had to be scraped together from various depots/sources.
The Germans had fuel shortages since 1941 already. In summer 1942 a whole Korps was immobilized in Russia, due to a massive shortage. In 1942, the italian Navy could not conduct major operations, due to the fuel shortage. Italy depended on German oil deliveries - Germany refused the Italian request to supply the Italian navy, which resulted in the italian decision to empty the battleships and distribute fuel to the destroyers. Germany lost the war in 1942 (some say at the Battle of Britain in 1940 [:D]), when the Germans couldn't secure the Russian oil fields. Starting at around 1941, the german oil supply situation was rather about taking away fuel or holding back fuel to fill the gaps elsewhere.
The gasoline reserves dropped from 4.125 times (peak in 1940) the actual monthly consumption to 1,75 times of the monthly consumption at the end of November 1944.
Until right before the start of the offensive the consumption increased to around 100,000 tons, while the gasoline stock had dropped to 130 - 135,000 tons.
These numbers tell a lot about the preconditions prior to the launch of this offensive, imho.
The Germans saved up fuel for several months and, in addition, they scraped together what they could find, in order to conduct the offensive. But, unlike in 1940, the distribution was faulty and hampered in 1944.
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This website here is maintained by a club of citizens/hobby historians in St. Vith.
@Panther-Bunnies:
I don't know if you'd rate these guys as thorough/reliable local researchers, but I know they cooperate with a historian from Aachen (surname is "Trees") too, and they talked to plenty of veterans/witnesses.
http://www.st.vith.be/60jahre/?Ardennenoffensive
http://www.zvs.be/
I've read an account on their pages that German units were only provided with fuel for 60 km at the start of the offensive. Well, that would be like 60% of the range of a panther tank (100 km), matching the statements of veterans i saw on TV.
Keeping in mind the difficult terrain in the Ardennes, 60 km seems to be really optimistic too.
Anyway, these guys might be able to point to records/resources.