Although most do not know this, Germans used camouflage during the war. The grey uniform was only ceremonial. However, they are pictured without the camo 99% of the time so I'd like to ask, during what years, on what fronts and in what quantity was it used. (I know they had tan uniforms in Africa so you don't have to tackle that)
This is going by memory of various Osprey series books so take this for what you will...
Throughout the war German troops wore field-grey uniforms. There were ceremonial versions but also ones for field use.
Early on (1939 to about 1942) the Waffen SS had multi-colored camouflage smocks that they would wear over top of their basic uniforms. Eventually this expanded to pants, hats, hemlet covers, etc. At that stage of the war the only cam-pattern kit the Heer (army) got was a shelter half/poncho.
Except for the winter of 1941 there was general issue of white camouflage once the snows hit. Prior to that distribution of winter whites was limited (e.g. to units in the USSR tagged with planned post-war occupation duties).
From about 1942-43 the Heer started issuing reversible jackets, white on one side and multi-colored cam pattern on the other.
Note that cam patterns for Heer, SS and paratroops all differed. I recall also reading somewhere that patterns could vary with theatre, specifically troops in Italy having different patterns than elsewhere due to requisitioned Italian supplies of cloth.