Want a 911 with a drop-top? Porsche currently offers six different varieties of Cabriolet and another couple of Targas, and you can bet there will be more to come. But that wasn’t always the case.

In fact there wasn’t a convertible Elfen until the one you see here – a rare type 901 convertible prototype that’s now going up for auction.

One of the highlights of RM Sotheby’s upcoming sale in Paris, this particular 911 is described as “one of the most historically important Porsche ever offered on the open market.” And with good reason.

During the course of its development, the German automaker fabricated thirteen 901 prototypes. This example is one of only two still in existence, and the only one built as a convertible. It paved the way for the first 911 Targa that emerged several years later, not to mention the first full cabrio to follow in 1982, and all the open-top models that have come over the course of the decades since.

Having played such a seminal role in the history of one of the most legendary sports cars of all time, the auction house expects the 1964 Porsche 901 Cabriolet prototype, chassis no. 13360, to sell for between €850,000 and €1 million when the gavel drops during Rétromobile week at Place Vauban on February 8, 2017.

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