The Porsche Cayenne recently celebrated a major production milestone as the one-millionth example rolled off the production line nearly 20 years after it was introduced. The idea of Porsche building an SUV was controversial when the Cayenne launched in 2002. But the German automaker was already exploring the possibility of selling a high-riding vehicle alongside its traditional 911 sports cars long before then.

Back in 1989, Porsche presented the Panamericana, one of the craziest 911 concept cars the firm has ever built. Named after the notorious Carrera Panamericana endurance race dominated by Porsche in the early 1950s, the Panamericana was a one-off concept built for Ferry Porsche as an 80th birthday present.

YouTuber That Nine Eleven Guy was recently given a rare opportunity to take a closer look at the rare concept car's unusual design cues at the Porsche Museum in Stuttgart. The unconventional roof is split into three sections with a zipped-up fabric above the front seats, two body-colored plastic sections that give a double-bubble appearance, and a perspex rear screen. While the roof inspired Porsche to design the Boxster roadster, the Panamericana was designed for driving off-road. The front and rear wheel arches were removed to allow for long-travel suspension and chunky tires, while the design was penned by Steve Murkett, who went on to help design the Cayenne and Panamera.

Despite being designed as a standalone model outside the 911 range, design cues from the Panamericana were added to later 911 models.

At the front, the headlights resemble a 993 911, while the cup mirrors were added to the 964 and the roofline inspired the design of the 993 Targa. In a nice touch, the Porsche crest logo is etched into the tires, which are wrapped around unique wheels. As for the engine, the Panamericana is powered by a 250-hp 3.6-liter flat-six taken from a 964 Carrera 4, which the concept is based on.

Inside, the marble interior is certainly eye-catching and the dials and center console are taken from the 964, but you won't find the seat designs in any other 911. Its influence cannot be downplayed, as the Panamericana inspired the future direction of the company as it diversified into other segments. Over 30 years after the Panamericana was built, the Cayenne and Macan SUVs are two of Porsche's best-selling models.