The Mercedes-Benz 300SL Gullwing is rare, desirable car. Yet this 1955 example is even more special.

Part of the outrageous Pinnacle Portfolio collection, this car is one of only 29 aluminum-bodied Gullwings built. It will cross the block next month in the RM Auctions sale held in conjunction with the Pebble Beach Concours d'Elegance and the other festivities of Monterey Car Week.

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In addition to its lighter bodywork, this Gullwing features the "Sonderteile" version of the 3.0-liter inline-six, with a competition camshaft that boosts output by 15 horsepower, to 215. It was originally white, and came with sports suspension Rudge wheels, and matching luggage. RM expects it to sell for between $5.5 million and $6.5 million.

The car was ordered new by industrialist Rene Wassermann, who picked it up from the factory and drove it to his home in Basel, Switzerland. At some point Wassermann sold the Gullwing, and after transitioning through a couple of U.S. owners, it made its way into the hands of Pennsylvania State Senator Newell Wood. The Senator was a racing enthusiast, and even received a lifetime membership from the SCCA for promoting road racing in the Northeast.

After Wood, the Gullwing was subsequently traded among several owners and received a restoration in Germany, where it acquired its current silver exterior color. It shows 2,481 kilometers (1,547 miles) on the odometer, presumably since that restoration, RM says.

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Sometime after the restoration, the car became part of the Pinnacle Portfolio, joining other classic sports cars as well as more modern supercars like a Jaguar XJ220, two Bugatti Veyrons, and a 1998 McLaren F1 built to "LM Specification," with the mechanical upgrades of the Le Mans racing version of the F1. The collection is valued at around $65 million, and is billed as the most expensive ever to be auctioned off.

The Pinnacle Portfolio auction begins August 14, as part of Monterey Car Week. For all of the latest news about the happenings there, head over to our dedicated hub.

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