Thanks guys.
CharlieC, I have no idea about real colors of armored cars from that period of time. I've paited it green according to the color of WAK's kit. In the kit you have 2 option of this model. Captured Polish car named 'WNUK' and car without any marks. Both of them are in dark green color.
I saw also this picture(
click).
It seems to be painted dark green.