In 1909, August Horch founded Audi, which is the Latin translation of 'Horch.' Early Audis had competition success. In 1932, four German car companies—Audi, Horch, DKW, and Wanderer—merged to form the Auto Union; the four linked rings in the current Audi logo represent the four companies. Along with racers from Mercedes-Benz, mid-engine Auto Union race cars originally designed by Ferdinand Porsche dominated motor racing in the 1930s. With the end of World War II, the leading staff founded a new company in the Bavarian town of Ingolstadt. Between 1964 and 1966, Volkswagen acquired the company and revived the Audi name for a newly designed car with a four-stroke engine. The car that launched Audi's modern reputation as a technology leader and maker of advanced, competitive cars was the four-wheel-drive Audi quattro in 1980. Audi's popular A4, A6, and A8 series cars first appeared in 1994, and the high-performance, all-wheel-drive S-series versions have been successful in amateur competition. Audi's Le Mans prototype race cars have played a dominant role at the top level of motor racing. In 2006, Audi introduced the diesel-powered R10 TDI, which won three consecutive 24 Hours of Le Mans in 2006, 2007, and 2008. In 2009, Audi introduced its latest Le Mans prototype, the R15 TDI, which won its first outing at the 12 Hours of Sebring in the same year.