The ultra-rare type 993 GT2 is the ultimate air-cooled 911, enthroned at the pinnacle of the last dynasty of production Porsches powered by the company’s iconic air-cooled flat-six engine.

Like so many exceptional road cars of the 20th century, it was the product of a racing program that required roadgoing variants be produced to meet homologation criteria.

In this case, the program involved Porsche’s efforts in the 1990s to compete with a turbocharged 911 in the Fédération Internationale de l’Automobile (FIA) GT2 class.

Using the type 993 911 Turbo as a starting point, Porsche reduced weight by more than 440 pounds, removing the all-wheel drive components and reverting the chassis to rear-wheel drive.

Much of the interior was stripped, including the back seats, sound deadening, and many creature comforts.

The windscreen was replaced with thinner glass, while the hood and doors were composed of lightweight aluminum.

Meanwhile, Porsche increased peak boost of the 3.6-liter engine’...