1977 was the last year for the Beetle coupe in the US. Why? From a New York Times article from August of that year: "In the United States, It has become a
victim of international economics, American safety and emissions
requirements and just plain changing times.
When
the dollar decreased in value relative to the mark, the beetle became
more expensive to United States consumers and therefore less
competitive. At the same time, according to spokesman for Volkswagen of
America, the cost of meeting American emissions and safety standards
helped to make the bug uneconomical.
Finally,
Japanese auto makers put severe competitive pressure on VW by bringing
out more stylish, up‐to‐date small cars for the American market. For
this and other reasons, VW changed its product."
The convertible received a reprieve of two years before it disappeared as well. With no convertibles built in the US after 1976, and the demise of the Beetle as well as the MG and the Triumph, by 1981 American convertible buyers were limited to a handful of German and Italian cars.