Do you have a cite that supports your assertion that the European Axis had a greater production of either aluminum or bauxite than the US and the Commonwealth? I find the idea hard to believe based on the figures I have seen and to which I posted a link. These figures show that in 1938 the US had produced around 28.5% of the world's aluminum. By 1942 the US was producing over 45% of the world's aluminum. Somehow I think that in 1942 the UK, Canada, and the Soviet Union were responsible for more than 5% . Of course, Japan would have to be taken into account, too. This makes it seem unlikely that the European Axis, even with seized Norsk Hydro assets produced more aluminum than the US, let alone the US and the Commonwealth.
This thread seems to support your figures:
http://forum.axishistory.com/viewtopic.php?f=66&t=161206
It seems the Germans produced electricity second only to the US, which means they had plenty and didn't really need to tap into coal, as they had lots of hydroelectric plants in the Alt- and Grossreich.
Also:
http://www.encyclopedia.com/doc/1O129-rawandsyntheticmaterials.html
Part of the problem with the 1938 figures though is that they don't indicate trade deals that Germany had set up with the Balkan states, Turkey, and Spain, which met her needs for most metals that Germany did not produce herself.
Part of the problem with Aluminum in Germany was that the manufacturers were requesting double what they needed to complete airframes, which meant they were hoarding it. When Speer found out in 1942 he requisitioned it, which helped boost production of aircraft to over 40,000 by 1944. Also major inefficiencies wasted a fair amount of materials: aircraft frame plants were scattered and did not centralize component construction to make it harder to bomb from the air. This badly affected efficiency, which prevented large scale assembly lines, like the one in Detroit that was over 1 miles long.
Also the constant emphasis on craft production over mass manufacturing, plus numerous, non-compatible variants to aircraft, contrary to suggestions by manufacturing experts in the LW and other economic planning offices, further wasted raw materials. It wasn't until 1943-44 that raw material usage became much more efficient.
The article about deconstructing Speer's armaments 'miracle' I posted earlier gets into all this and more.
http://en.wikipedia.org/wiki/Mediterranean_Bauxite_Province
Also Germany had access to Yugoslav bauxite from 1938 on and from 1940 on the southern French deposits.
Mediterranean Bauxite Province - a major region of high-quality bauxite ores that stretches for 3,000 km along the northern shore of the Mediterranean Sea from Spain to Turkey, encompassing parts of southern France, Italy, Yugoslavia, and Greece. The province covers an area of about 2 million sq km.