Aug. 15 (UPI) -- An 80-year-old, one-of-a-kind German sports car -- said to be the first car ever to carry the "Porsche" nameplate -- is on the auction block this weekend, where it's expected to fetch at least $20 million.
RM Sotheby's will sell the 1939 "Porsche Type 64" Saturday at its Monterey County, Calif., auction house.
German auto engineer Ferdinand Porsche designed the Type 64 car as a racing version of the KdF Wagon -- which would later evolve into Volkswagen's Beetle -- for a Nazi Party rally from Berlin to the Austrian Alps to Rome. It was built with a lightweight alloy body and more than 2,000 rivets using aircraft technology, and turned the KdF Wagon's sub-40-horsepower engine into a powerful racing machine.
The race never took place because of the outbreak of World War II, but three Type 64s were built -- and just one survived the war.
Although engineered a Volkswagen, the Type 64 is believed to be the first car ever to bear the "Porsche" badge. Nearly a decade later, the first Porsche 356 was unveiled on a racetrack in Innsbruck -- officially launching the now-iconic high-performance automaker.
Sotheby's said the top speed of the Type 64 is about 90 miles an hour, and with no muffler or soundproofing, it's not a quiet ride.
Frank Jung, head of historical archives for Porsche, told CNBC the 356 is technically the first Porsche -- and the Type 64 a "race version of a pre-Volkswagen."
He added, though, the Type 64 is still a "very important piece" of Porsche history.
Sotheby's calls the vehicle "the most historically important Porsche ever publicly offered."
Though entirely unique, the Type 64 is not expected to even approach the all-time auction record price for a car. A 1962 Ferrari 250 GTO -- that sold for $48.4 million last year -- holds that distinction.