The original Porsche 911 (pronounced nine eleven, Neunelfer) is a luxury sports car made by Porsche AG of Stuttgart, Germany. The famous, distinctive, and durable design was introduced in autumn 1963 and built through 1989. It was succeeded by a modified version, internally referred to as Porsche 964 but still sold as Porsche 911, as are current models. Mechanically, the 911 was notable for being rear engined and air-cooled. From its inception, the 911 was modified both by private teams and the factory itself for racing, rallying and other types of automotive competition. The original 911 series is often cited as the most successful competition car ever, especially when its variations are included, mainly the powerful 911-derived 935 which won 24 Hours of Le Mans and other major sports cars races outright against prototypes.