Top 5 most expensive cars ever auctioned: 1955 Mercedes-Benz 300 SLR Uhlenhaut Coupé ($143m), 1962 Ferrari 250 GTO ($51.7m), 1955 Ferrari 121 LM Spider ($22m), 1956 Ferrari 290 MM ($28m), 1935 Mercedes-Benz 540K Special Roadster ($9.9m). Between them, Mercedes and Ferrari account for eight of the ten most expensive cars ever sold at auction.