That is Opel's that were rebadged and had some cosmetic changes, in Brazil they were sold as Chevrolet Opala, in Australia as Holden Commodore.
The Opel Rekord and the 6-cylinder Commodore were the bread and butter car for most of Europe in the 50's to 70's. Body styles were very much influenced by Chevrolet design. Especially in the C-line (1967-1971) you'll see the lines of Chevelle/Malibu.
They had very small wheels back then, only 13" rims on the Rekord and 14" on the Commodore (it had larger brakes)
Here are some pictures of various models found on Google.
The Coupé
2-door Sedan
4-door Sedan
2-door Wagon
4-door Wagon
The Commodore had straight 6-cylinder engines. the 6-banger could also be specialordered for the Rekord, very rare. There were also convertibles made by a German coachwork company. And then the special Opel Rekord Sprint with the 2-liter, dual 2-barrel carb hi-perf engine.
Great cars that ran well, I had a bunch in my youth.