Mecum Auctions' Monterey 2013 sale has been highlighted by a magnificent 1955 Porsche 550/1500 RS Spyder, which led bids on August 15-17.
The Porsche, consigned from the Peter and Cheryl Dunkel Collection after nearly 25 years of ownership, crossed the block at $3.7m.
The Porsche 550 was introduced at the 1953 Paris Motor Show, as the marque's first dedicated sports racer. The decision to produce the car came in response to stiff competition from a new breed of sports cars specifically geared for larger European circuits.
The car went on to secure class wins at the Mille Miglia, Le Mans and the Carrera Panamericana in 1954, spurred by its incredibly complicated yet powerful Type 547 engine.
Following this success, Porsche began building customer cars, replacing the ladder-type frame with a stronger space frame to improve high-speed stability.
The present example, delivered new to Belgian race driver Christian Goethals, is believed to have been the first car fitted with the new chassis.
Featured by Porsche at the Brussels Salon Auto Show in 1955, it was actively campaigned by Goethals in Europe, before heading to the US for five years of racing at the hands of Suzy Dietrich and Tom Payne.
It was then passed to the Dunkels in 1989, who gave it a full restoration, with the help of the world's leading authority on the Type 547 4-cam engine, Bill Doyle.
Also featuring was a 1990 Ferrari F40, prized for the fact that it has only had one owner from new and has only 473 miles on the odometer. Kept in storage for much of its life and in superb condition, it sold for $1.3m.
The record for any Ferrari at auction was set at $27.5m by a 275 NART Spyder at RM Auctions' Monterey sale, while Bonhams' Quail Lodge auction - also held as part of the Pebble Beach Concours d'Elegance - was topped by a $4.6m Blower Bentley from the collection of Charles Noble.