The oldest surviving sports car built by Porsche, and first to wear the brand’s name, is heading to auction this summer and expected to sell for a historic price.

(RM Sotheby's)

The Type 64 was the third of a series built by Ferdinand Porsche and his son Ferry between 1939 and 1940.

(RM Sotheby's)

Based on the chassis of the KdF-Wagen, which was also designed by the elder Porsche and would spawn the Volkswagen Beetle, the Type 64 was originally built to compete in a race from Berlin to Rome that was canceled after the outbreak of World War II.

(RM Sotheby's)

By then only one of the sleek, aluminum-bodied cars had been finished, but Porsche continued the program and built a second followed by a third on the chassis of the original, which had been damaged in a crash by the managing director of Volkswagen.

(RM Sotheby's)

The second car was discovered in storage by U.S. occupying forces, who turned into a convertible and discarded it when it broke down. It was dismantled, but has since been rebuilt from spare parts with a new body and was recently on display at the Petersen Automotive Museum in Los Angeles.

(RM Sotheby's)

The Porsche family kept the third intact and added a nameplate to it after the company was registered in 1946, with its first official production 356 models to follow in 1948. The 64 was sold the following year to an Austrian racer, who kept it until his death in 1995. It was subsequently acquired in 1997 by noted Porsche collector Dr. Thomas Gruber, who is the one offering it at the RM Sotheby’s event in Monterey, Calif., in August.

RM Sotheby’s hasn’t put an estimate on the value of the car, but a $20 million figure is being bandied about in the collector car world. That would make it the most expensive Porsche ever sold, eclipsing the $14 million high bid placed on a 1971 917 race car featured in the Steve McQueen film, “Le Mans,” at an auction in 2017.

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