Possible Clues:

• Multi-octave old-school crooner Jackie
• European G.M. division
• Real gem of a car?
• "Cry Me a River" Barbados singer Jackie
• General Motors subsidiary in Germany
• German car first shown at the 1902 Hamburg Motor Show
• ''Wir leben Autos'' sloganeer
• German-based G.M. subsidiary
• Volkswagen rival
• Berliner's wheels, perhaps