1955 Mercedes-Benz 300SL Gullwing sells for $9.5 million

A 1955 Mercedes-Benz 300SL ‘Gullwing’ has sold at auction for $US6.85 million ($AU9.5 million) in the USA.

The two-seater – stamped chassis number 5500332 – is one of just 28 examples ever built by Mercedes-Benz with an aluminium body, which was designed to shed weight and improve handling in competition.

The original number-matched 158kW/294Nm 3.0-litre straight-six petrol engine is retained, however the blue gabardine fabric upholstery and four-speed manual transmission were swapped out during a 1979 restoration. 

Factory-fitted sports suspension, a high-speed rear axle, metric speedometer, underbody protection, and 'Rudge' steel wheels feature, as does an original Becker radio.

The vehicle went under the hammer at an RM Sotheby's event in Arizona last week, where a steel-bodied version of the 1955 300SL found a buyer at $US1.71 million ($AU2.4 million).

The rarity and performance credentials of the aesthetically-identical aluminium car are believed to account for the significant price difference.

It's unclear who bought the car or where it will now be kept, however Drive will update this story if more information becomes available.

The most expensive Mercedes-Benz ever sold was Juan Manuel Fangio's 1954 Mercedes-Benz W196 Formula One car, which in 2015 set a new record of $US29.6 million ($AU42 million).