GOING ONCE...
Innovative, powerful, luxurious, and often imitated, the most expensive cars in the world are one part engineering masterpiece and one part work of art. The world's most well-heeled collectors bring their checkbooks to elite auctions hoping to drive home (hopefully not literally) with a Porsche, Ferrari, Aston Martin or Alfa Romeo that won races, was owned by royalty, or that can't be found anywhere else.