During WW2 the German army mandated the base colour that factories had to use and for most of the war they supplied AFVs, trucks and artillery just in that one colour. Any additional camouflage was applied by unit workshops, or more commonly by the individual crews. At the beginning of the war the base colour was a dark grey but in 1941 this became an issue as the war was being fought on the Russian Steppes and in North Africa, where the terrain was predominately brown. Afrika Korps vehicles got their own two-tone brown scheme first. Then in 1943 the base colour for other fronts was changed to dark yellow, which is actually a light brown. Cans of red brown and dark green were made available to crews to paint their own camo schemes over this to better match local conditions, the usual disruptive scheme being one third of each colour.
Towards the end of 1944 tank factories were ordered to paint camo schemes onto the vehicles themselves. This was mostly to hide them from Allied aircraft which were interdicting the vehicles as they were transported to the front. In January 1945 the factories were ordered to make the base colour green, with the other two colours as disruptive camouflage. This was partly due to a shortage of dark yellow paint and partly due to the war now being fought on mostly green German spring terrain.
Apart from the Sd Kfz 251, Panzer IVF and a few very early Tiger Is all German vehicle variants in AH are from the base dark yellow or base dark green periods. However determining which scheme was used from a photo can be tricky. The biggest giveaway is the shade of the wheels as these were seldom camouflaged in the field (a rotating two-colour wheel tends to draw the eye of the enemy). Also the photo needs to be from 1945, although there were still base dark yellow vehicles running around at this time.
I make an effort to skin base dark green vehicles when I can find them but the overwhelming majority of photos are of base dark yellow ones.
