6. 1933 Alfa Romeo 8C 2300 Monza Roadster – $11,990,000
This car is one of 190 8C 2300 chassis built—but since most of those cars ended up as luxurious touring vehicles, it’s a rare find. It’s racing history extended for over 60 years, and in the 83 years since it was built, the car has had just four owners. 