Rust spots, chipped paint, and a totally worn interior are not what you normally associate with a priceless classic car. But this Mercedes 300 SL Roadster is unlike any other, as it was owned by none other than legendary racing driver Juan Manuel Fangio. It is soon coming up for auction. Expect it to fetch megabucks—even in its current, well-worn condition.

Unsurprisingly, the connection between Fangio and Mercedes-Benz is a rather special one. The Argentinian won two of his five driver’s titles in Formula 1 in Silver Arrows, in 1954 and 1955. But the mutual respect was not limited to motorsports. Even before he became a Mercedes works driver, Fangio was selling Stuttgart-made products in Buenos Aires in the shape of Mercedes taxis. He later set up an engine plant for the Swabians in his homeland, and also acted as head of the Argentine branch, as well as brand ambassador for South America. In 1987, the automaker even appointed him honorary president for life.

Although Fangio completed his final seasons for Mercedes rivals Ferrari and Maserati, and even won his last two world titles with them, it was not the Italians but the Germans who gave him a special farewell gift: He was presented with a 300 SL Roadster, finished with a light-blue metallic body and a cream-colored interior as a nod to Argentina’s national colors. This is the car that will soon be auctioned off by RM Sotheby’s in the posh Swiss ski resort of St. Moritz as part of a private event. A lot of people would have taken such a gift and stored it carefully in their garage, never to really use it. Not so Fangio. The maestro loved his Chedeng so much, he put plenty of miles on it. The odometer currently reads 72,951km, and it is believed that the famous owner put most of those on the car himself.

Everything else about this German convertible is also well documented. The SL with the chassis number 198.042.8500083 was built in the Stuttgart-Untertürkheim plant in 1958, and presented to Fangio in London on his 47th birthday. From there, it went on a tour of Europe before being shipped to Argentina in 1960. After “El Maestro” finally got his driver’s license (he actually completed his entire racing career without being able to legally drive a car on public roads), the SL became one of his favorite cars, and there are plenty of photographs around showing him behind the wheel. It may even have been used in some motorsport events in the past, and Fangio also employed a mechanic who had been especially trained in Germany to maintain the car.

The condition it is in today is pretty much the same as it was when it was rolled into the official Fangio Museum in his hometown of Balcarce back in 1986. The auction house speaks of wear and tear as caused by the great man himself, and there’s no doubt that there’s something magical about the condition of this car. It still has the aftermarket gear knob the champion racer fitted himself, and the Grand Prix Drivers’ Association sticker is still attached to it. Needless to say, this machine is sold as a Matching Numbers example, with chassis, body, engine, transmission, and differential still all original.

The fact that this vehicle is something very special is also illustrated by the unusual procedure in which Sotheby’s is auctioning off Fangio’s 300 SL. There won’t be the usual bidding competition: If you want the Roadster, you must write down the final price you are willing to pay in advance. The sealed bids are then compared, and whoever offers the most wins. An interesting procedure that unfortunately has one major disadvantage for us: The auction house will not publish the sale price.