Well, things are a bit more complicated here.
When the Wartburg appeared in 1956, it was just called Wartburg, the internal code was 311, but that did not appear on the car or in brochures. When the engine was enlarged to 1000 cc in 1962, it was called Wartburg 1000, the internal code remained 311. At the end of 1965, an interim model appeared featuring the old body on the new chassis designed for the Wartburg 353 to come. This interim model was called Wartburg 1000 as well as Wartburg 312, I have seen both emblems on these cars. The 312 is recognizable by its wheels which were smaller than those of the 311.
The puzzle car appeared in 1965 as a new, modernized body style, the hardtop coupe, built by KWD (Karosserie-Werke Dresden, formerly Gläser). It was called "Wartburg 1000 Coupé" or "Wartburg 1000 Coupé als Hardtop" or "Wartburg 1000 Coupé hard-top" or "Wartburg 1000 Coupé HT". It should have been built on the new chassis from the beginning, but that wasn't ready then. So the first 168 of the 709 cars built, used the old chassis. Those were called "Wartburg 311 300 HT" in the cars' documents, those with the new chassis were called "Wartburg 312/1 300 HT".
The puzzle picture was used in a brochure for the 1000 Coupé hard-top with the new chassis 312, but in fact it shows a car with the larger wheels, alas the the old chassis 311.