1955 Mercedes-Benz 300 SL Alloy Gullwing - $6.8m

A rare 1955 Mercedes-Benz 300 SL Alloy Gullwing sold for $6.8m at RM Sotheby’s Scottsdale auction. It set a new record for the iconic model. A 1955 Alloy Gullwing that sold for $4.2m at Gooding & Company’s Scottsdale auction in 2012 falls to 2nd place. Chassis number 5500332 is one of only 24 aluminum Gullwings built. It is one of a handful to retain its original, numbers-matching 3.0-liter NSL inline-6 engine, high-speed 3.42 rear axle, front spindles and Rudge wheels, as well as the authentic alloy body and factory-correct livery.

The M186 Engine was a 3.0 litre single overhead camshaft inline 6, developed in the early 1950s to power the company's new flagship 300 "Adenauer" (W186) four-door saloon. It made its debut at the Frankfurt Motor Show in April 1951. Various versions of the engine (M186 – M199) produced from 115–240 bhp.