A 1938 Bugatti type 57C Stelvio convertible led Bonhams' Greenwich Concours d'Elegance sale in Connecticut on May 30 with a final bid of $1.5m.
The exceptional lot features coachwork from renowned maker Gangloff and is a rare original example of a supercharged Bugatti.
The auction house commented prior to the sale: "Over the course of the last decade or more the car has been cherished and enjoyed by its current Bugatti aficionado owner…
"Since that time, its use has been limited. As evidenced from its visual presentation, even among the more commonly produced coachwork designs each and every car has its own personality.
"In the opinion of Bonhams specialists, this is a particularly good looking example of Gangloff's late Cabriolets."
A 1973 Porsche 911 was another highlight, achieving $594,000.
The model was originally delivered to Brazil and while not eligible for Concours in its current condition, remains in good condition.
Other lots in the sale included a 1938 Jaguar SS100, which made $231,000.
It was dismantled and partially re-assembled by its previous owner and offers an enjoyable challenge to the buyer.
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