The GT40 was created by Ford in the early 1960s to beat Ferrari at long-distance sports car races, after the US auto giant failed to buy the Italian company in 1963. The car won the Le Mans 24-hour race for four consecutive years from 1966-69.
The version at RM (chassis P/1074) had been raced by Jacky Ickx at Daytona and Le Mans trials in 1968. It was later used as the camera car in Steve McQueen's 1971 film Le Mans.
The first day of the RM sale raised about US$46 million with 55 of the 60 offered cars successful, said the auction house.
Other highlights included a cream-coloured 1955 Ferrari 410 S Berlinetta that sold for US$8.25 million. Made with a competition-power engine for Michel Paul-Cavallier - a director on the board of Sefac, Ferrari's corporate racing entity during the 1960s - the car raised a record price for this particular model, RM said.
"The prices of the rarest Ferrari road cars have now pushed on," Hatlapa said. "Two years ago, this 410 S would probably have sold for less than US$5 million."
Earlier, a restored Ford GT40, formerly owned by the Bolivian tin magnate Jaime Ortiz-Patino, sold for US$2.2 million on the second day of a Bonhams auction of classic motorcycles and cars at Quail Lodge, Carmel.