Opel, wholly owned by General Motors by 1931, introduced its Kapitän line in 1939, just before the war started. (Kapitän, in German, refers to the naval rank equivalent to a colonel in the army or a ship's captain. An army captain in Germany is called a hauptmann. For many years Opel favored naming its lines after ranks, including Kadett, Admiral, Diplomat, Commodore, this to indicate the line's degree of assigned prestige.) Information regarding the Kapitän line can be found here.
The postwar Kapitän was introduced for 1947, and was almost identical to the 1939 model, the visible change being that the '47 had sealed-beam headlights. A facelift was added for 1951-1953 models. The most noticeable difference was a new grille with large, chromed bars in the contemporary American fashion.
Below, for your viewing enjoyment are some Opel publicity photos featuring 1951-vintage Kapitäns.