operation of the company, including F. A. Porsche and Ferdinand Piëch, departed from the company. F. A. Porsche founded his own design company, Porsche Design, which is renowned for exclusive sunglasses, watches, furniture, and many other luxury articles. Louise's son and Ferry's nephew Ferdinand Piëch, who was responsible for mechanical development of Porsche's production and racing cars (including the very successful 911, 908 and 917 models), formed his own engineering bureau, and developed a five-cylinder-inline diesel engine for Mercedes-Benz. A short time later he moved to Audi (used to be a division, then a subsidiary, of Volkswagen), and pursued his career through the entire company, ultimately becoming the chairman of Volkswagen Group. The first chief executive officer (CEO) of Porsche AG was Ernst Fuhrmann, who had been working in the company's engine development division. Fuhrmann was responsible for the so-called Fuhrmann-engine, used in the 356 Carrera models as well as the 550 Spyder, having four overhead camshafts instead of a central camshaft with pushrods, as in the Volkswagen-derived serial engines. He planned to cease the 911 during the 1970s and replace it with the V8-front engined grand sportswagon 928. As we know today, the 911 outlived the 928 by far. Fuhrmann was replaced in the early 1980s by Peter W. Schutz, an American manager and self-proclaimed 911 aficionado. He was then replaced in 1988 by the former manager of German computer company Nixdorf Computer AG, Arno Bohn, who made some costly miscalculations that led to his dismissal soon after, along with that of the development director, Dr. Ulrich Bez, who was formerly responsible for BMW's Z1 model, and was CEO of Aston Martin from 2000 to 2013. In 1990, Porsche drew up a memorandum of understanding with Toyota to learn and benefit from Japanese lean manufacturing methods. In 2004 it was reported that Toyota was assisting Porsche with hybrid technology. Following the dismissal of Bohn, Heinz Branitzki, a longtime Porsche employee, was appointed as interim CEO. Branitzki served in that position until Wendelin Wiedeking became CEO in 1993. Wiedeking took over the chairmanship of the board at a time when Porsche appeared vulnerable to a takeover by a larger company. During his long tenure, Wiedeking transformed Porsche into a very efficient and profitable company. Ferdinand Porsche's nephew, Ferdinand Piëch, was chairman and CEO of the Volkswagen Group from 1993 to 2002 and is chairman of the Volkswagen AG Supervisory Board