AUDI AG (Xetra: NSU) is a German manufacturer of automobiles marketed under the Audi brand, German pronunciation: [ˈaʊdi]. The company is headquartered in Ingolstadt, Germany and has been a wholly-owned (99.55%) subsidiary of the Volkswagen Group (Volkswagen AG) since 1964. Volkswagen Group relaunched the Audi brand with the 1965 introduction of the Audi 60 range. Shortly thereafter the name was acquired as part of Volkswagen's purchase of the Auto Union assets from former owner, Daimler-Benz. The company name is based on the surname of the founder August Horch, the name itself a English cognate with the English word "hark", meaning listen — which when translated into Latin, becomes Audi.
Source : http://en.wikipedia.org/wiki/Audi