Saab was actually an aeroplane manufacturer, but in 1947 the company also began producing passenger cars. These were characterised by advanced construction and aerodynamic styling. It began with the Saab 92, which developed into the Saab 93 and 96. Originally two-stroke engines were used, but the company soon switched to four-stroke engines, which were also fitted with turbochargers in the 1970s (including the Saab 99 and Saab 900), making it one of the pioneers in this field. Sports cars were also built with the Saab Sonett, but saloons remained the main focus of car production. In 1989, General Motors became a shareholder in Saab, and Saab models were subsequently also built on GM platforms. By 2008, GM had lost interest in Saab and the receivers moved in. A takeover by Koenigsegg and later Spyker and the continuation of car production were not successful. Although a relaunch with electric vehicles has been rumoured several times, it has not yet materialised.