Do you know why this car is expected to sell for $12 - $15 Million ??

A spectator (below) views one of the 1930's silver arrow cars, a fabled 1939 Auto Union D-type racing vehicle, said to be one of the most important cars in motor racing history, attracts media attention at an Audi of America dealer on Park Avenue in New York, Thursday, Jan. 25, 2007, during a public viewing before the car is auctioned off at Retromobile February 17 in Paris. Christie's, who is bringing the car to auction, is expecting bids in the region of $12 to $15 million for the car. The Auto Union's revolutionary design, conceived by Ferdinand Porsche, place the driver in front of the engine and fuel tanks, with all four wheels benefiting from independent suspension. Only five of the final model D-type Auto Unions remain, and this example is the only privately-owned model. (AP Photo/Kathy Willens)