The ZIM till 1956 is the GAZ-M-12. The ZIM was sometimes designated as the GAZ-12. It is a Soviet 6-7-seat high-performance car with the body, which represents a 6-window long-based sedan, series-produced at Gorky automobile plant (the plant named after Molotov) from 1950 till 1959 (some modifications were produced till 1960). The car of high-performance class was designed for Soviet party and government nomenclature on the level of ministers, regional party committee secretaries and regional executive committee chairmen.

The ZIM became the first world car with three rows of seats in an integral body. A hydro mechanical transmission, providing soft acceleration and ease of transmission control, was implemented for the first time in the domestic practice in this car. The first show of the car took place during the holiday demonstration on the 7th of November in 1948 in Gorky. The serial production started in 1949.

All in all 21,527 copies of ZIM-GAZ-12 were made from 1949 till 1959. The major distinctive feature of the car was its body. It was made integrated, that is it did not have a mechanically detachable frame. Load-bearing elements, actually analogue to the frame (sub frames) were fastened with welding or bolted up at the ends of the body. Such a design of the body in general gives some advantages in the structural weight. Though an integrated body was not a unique thing for those years, it was used exceptionally rare in the cars of this class, and it did not occur at all (and very rare later on) in the models with a wheelbase, comparable to the ZIM with three rows of seats. Therefore Gorky designers were the first in the world who created the car of such a class with an integral body.