Fifth-costliest car: 1955 Ferrari 410 Sport Berlinetta
This car is one of four 1955 401 Sports ever built, but has a different body type than the other three.
Ferrari specifically designed its four '55 410 Sports to compete in the five-day Carrera Panamericana road race between Texas and Mexico -- although none actually did. The annual race was canceled for decades after the 1955 Le Mans tragedy, where a race car flew into the crowd and killed 83 people.
The 410 Sport that sold at auction in 2012 boasts a mammoth, 345-horsepower V-12 engine.
But it's the car's design -- a coupe for everyday driving instead of an open-topped car for racing -- that really boosted its price.
Experts say the vehicle, which famed designer Sergio Scaglietti custom-built for a Ferrari board member, represents an early version of a look that eventually evolved into the legendary Ferrari Testa Rossa.
"It's like you went to Ferrari and had them build you a Formula 1 race car but put a [roof] on it so you could drive it on the road," says RM's Girardo, whose firm handled the vehicle's sale.