Renault, Peugeot, and FIAT were popular in the '70s and '80s. VW didn't enter the market until 1980, when they bought Chrysler Argentina and kept building the local version of the Hillman Avenger, the Dodge 1500, as the VW 1500 until the early '90s, I believe. The Renault 12 and Peugeot 504 were popular as taxis.
During the '70s Ford built the Fairlane, Taunus (German equivalent of the Cortina), and Falcon. The Falcon, which got many, many facelifts, was built until 1991, and was notorious as being the car of the secret police during the days of the military regime. Dark green Falcons were the scariest cars in the country.