(CNN) – The great-grandfather of the Porsche 911 is going up for auction this summer, and it may end up being the most valuable Porsche ever sold.
The Porsche type 64 was Ferdinand Porsche’s early attempt at a sports car and has its engine in the rear.
It will be auctioned through RM Sotheby in mid-August in Monterey, California.
Experts at Hagerty, a company that insures collectible cars, say as the earliest Porsche sports car, and with a direct lineage to today’s 911s, it could be worth between 20 and 25 million dollars.
Until now, the highest price ever paid for a Porsche at auction was 14 million dollars in 2017. It was a 1970 Porsche 907 race car that was used in the Steve McQueen movie “Le Mans.“