The Stug did so well due to it's excellent parentage in the Panzer III. First manufactured in 1937 the Pz III was
exceptional for its time. Well balanced in all ways as to crew placement, very reliable as the weight wasn't too
high and so on.
Total production of Panzer III and Stug for the war was 17,159 with a combined total of tanks killed exceeding 30,000.