Germany was critically short of all the raw materials (and especially fuel) needed to run a 20th Century war. By the same token, Japan was also naturally bereft of the raw materials needed to make weapons
and fuels.
Once the Germans lost access to the Romanian oilfields, their fate was sealed. At the same time, Hitler's absurd make or break vanity project- the siege of Stalingrad, broke the back of the Wehrmacht.
Also, by 1944, even Britain was out-manufacturing Germany...
