As a young man Haefner went to work in the auto industry as an employee of the Swiss division of General Motors Corporation. He eventually moved to England where he acquired an automobile franchise before returning home to open a Volkswagen dealership. Recognizing the important role a computer could play in his growing chain of dealerships, in 1957 Haefner became one of the first in Switzerland to import an IBM system for Business use. This led to his 1964 creation of Automation Center A.G., a computer services company in Zurich. In 1976 he expanded operations to the US and, after merging his company with Russell Artzt's and Charles Wang's publicly owned software company, Computer Associates International, Inc., in 1987, Haefner was CA's largest individual shareholder until his death. He continued to own AMAG Automobil- und Motoren, a highly successful Swiss automobile dealership chain. Until his death, at age 101, he was the oldest person worth more than a billion dollars.