Price: $9.7 million
Auction: Christie's, London 1987
This car was sold over two decades ago and still holds weight on this list. That's likely due to the fact that this 15-foot masterpiece is one of only six ever built. Ettore Bugatti originally planned to build 25 of these impressive machines and sell them to royalty, hence the regal name, but even European royalty wasn't trying to blow money during the Great Depression Era. As a result, none of the the six Royales were ever sold to any royals. This particular car is straight out of Ettore's personal collection, as it was preserved in a garage on his estate, surviving WWII behind a protective wall.
It's massive front-end makes room for an enormous 12.7-liter engine originally meant for an aircraft. To this day, it's one of the largest engines ever fitted for a car, making this one of the biggest and most highly sought after automobiles ever created. All of the remaining Royale engines were later used for high-speed Bugatti railcars. Maybe Ross and Diddy should get their weight up and look into one these real street machines. You ain't a true Bugatti Boy until you cop the Royale, like this dude in Japan did when he took the highest bid back in '87.