A 1963 Ferrari 250 GTO racer has become the world’s most expensive car, selling for $52 million.

The red competition car, formerly owned by the Greenwich, Connecticut-based collector Paul Pappalardo, was acquired by an unidentified buyer in a private transaction, said three specialist traders who independently confirmed the purchase and price to Bloomberg News. Recently, the car has been owned by a Spanish collector, the car website Barchetta said.

The car was recently in the hands of a Spanish collector. It has now been sold for $52 million, car dealers aware of the transaction told Bloomberg.

The price is a 49 percent increase on the record for any auto, achieved last year for another 250 GTO. Values of classic cars, particularly Ferrari’s of the 1950s and 1960s, continue to grow, attracting new enthusiasts, investors and speculators — and prompting fears of a bubble in the market.

“Today the GTO is considered the top car to own,” the California-based dealer Don Williams of Blackhawk Collection said in an interview. “It’s like the Mona Lisa. It has a mystique. If you have a GTO, you have a great collection.”

The car was acquired by Pappalardo in 1974, restored and subsequently driven by the collector in many historic races, including the 2002 Le Mans Classic, before being sold on.

“We don’t confirm these things,” Pappalardo said when telephoned last night. “I have no comment.”