Thanks. And why is the color scheme of the flak truck completely different from the other units? Looks pretty ugly because it is out of place.
One of the reviews said that the Flak Trucks were OKW's version of base buildings. If you'd look closely, you'd realise it's sandbagged in pretty heavily, and the Flak Guns are it's personal defense (since it can't carry the MG bunkers with it). The trucks are kinda like Opels, granting resources but being fragile, so there's a risk / reward factor in actually putting them out there.
Personally I think trucks would have fit the Americans better, since we were the only fully mechanised Army in WW2, where for every platoon of soldiers, we had a truck to carry them. On the other hand, the Russians walked and the Germans used horses.