The S-Type Mercedes-Benz - the supercar of its generation that easily reached over 100mph - still runs perfectly despite not being driven since 1952.
One of the world's fastest vehicles when it rolled off the production line in 1928, the Mercedes sparked a bidding war at the Bonhams' Goodwood Revival sale in Sussex, the Daily Mail reported.
The car has been owned by the same family since the 1920s and went to a mystery buyer for 2,801,500 pounds.
The 680 S-Type was one of the earliest mass produced luxury sports cars and boasted an engine designed by chief engineer Professor Ferdinand Porsche.
Experts hailed the dark battleship grey convertible, which had been languishing in a lock up without seeing the light of day for 60 years, as 'an incredible find'.
The 6.8-litre fast tourer was first registered on the roads in May 1928 and unrestored cars of its type are extremely rare.
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The car still has just 13,478 kilometres on the clock.
"It proved to run incredibly well, ticking over with jaw-dropping silence and driving very nicely," according to Bonhams.
Bonhams also said it was 'almost without precedent' for a family to own such a car for 84 years, calling it "an achingly-rare Mona Lisa of the automotive world".
The bodywork of the car was hand crafted by London-based coachbuilders Cadogan Motors and its original blue upholstery is still intact.