Halfway through the 1950s, Plymouth tasked designer Virgil Exner to make up the ground lost to the Ford and General Motors styling departments. He quickly made his mark, and the 1957 Plymouth model range forced the rivalling companies to re-asses their own designs. One of the possible next steps to improve the appeal of the Plymouth products was to extend the range with a sports car. To test the water, a show car was developed.
Designing a sports car was a long held ambition for Exner and in his honour the car was dubbed the 'XNR'. He penned a radical, asymmetric roadster, which borrowed cues from both the contemporary Watson Indy Roadster and the Le Mans winning Jaguar D-Types. The first sketches were made from late 1958 and were followed by a 3/8th-scale clay model. The actual body for the show car was constructed by Carrozzeria Ghia in Italy, following the design drawings made back in the United States.
As mechanical basis for the XNR, the shortest available chassis in the Chrysler family was picked, normally used for the Plymouth Valiant and Dodge Lancer. A complicating factor was that this was the first unitary chassis constructed by Chrysler since the Airflite of the 1930s. This meant that the top half of a virtually complete car had to be cut off the chassis before it was shipped to Italy. Here Ghia hand-formed the body in sheet-steel over a purpose-built armature and mated it to the Plymouth chassis.
Also carried over from the Valiant was the all-new straight six engine. Known as the '30-D Economy Six', it featured an unusual 30° cylinder angle. Slanted to the right, this allowed the tall engine to be used in a relatively compact and low engine bay. For the XNR, the 2.8 litre unit was fitted with a high-performance kit, which included a four-barrel carburettor and specifically cast headers complete with double side exhaust pipes. In this specification, the 'Slant Six' produced around 250 bhp.
From every angle, the Plymouth XNR was a striking machine. The long nose was inspired by single seater racers of the day and featured a full-width grille, which also housed the double headlights. The engine cover sported an off-set ram air intake, which formed one piece with the driver-side dashboard cover. Driver protection was limited to a small wrap-around screen, while the passenger had to make to do with a classic flip-up windscreen. Taken directly from Exner's much loved D-Type was the tail fin mounted behind the driver.
Although not displayed at any major show, the completed XNR did appear in a period newsreel and a eight-page promotional brochure was also published. Thanks to its production-based chassis and steel body, the XNR was a fully functional machine and Exner wanted to prove the car's merits on the test track. At an initial run he himself reached a top speed of 230 km/h (143 mph). Piloted by Dick Burke and fitted with a low-drag fibreglass nosecone, it eventually topped out at 245 km/h (152 mph).
Reportedly considered for production, the Plymouth XNR eventually remained a one-off. Some of its design cues, however, were used on later Plymouth models. For liability reasons, American manufacturers often decided to destroy show cars once they had completed their promotional duties. The XNR was fortunately saved from this fate by returning it to Ghia in Italy. They sold it to a Swiss enthusiast, who soon after passed it on to Mohammed Reza Pahlevi, who was better known as the Shah of Iran.
This was the start of a journey through the Middle East from Iran to Kuwait and finally Lebanon, bringing the car close to destruction several times. During the 1980s, it was acquired by a Lebanese enthusiast. He had come across the car by chance but did remember reading about it before in a Swiss book. In the following years, the car was moved from garage to garage to ensure it would survive the ever more violent Lebanese civil war. Defying the odds, the XNR eventually emerged relatively undamaged.
The Lebanese owner was keen to have Exner's masterpiece restored but struggled to find someone who would take on the daunting task to return the one-off to its former glory. He finally found RM Restorations willing to do the job and he shipped the car to Canada in 2008. During he restoration process, invaluable was the access provided by Virgil Exner Jr. to his father's archive of the car. This allowed the restorers to rebuilt and reconstruct many of the XNR's unique features.
The work was finally completed in March of 2011 when the car made its post-restoration debut at the Amelia Island Concours d'Elegance. A few months later, the Plymouth XNR was shown at the Pebble Beach Concours d'Elegance. Here it was awarded the Gran Turismo Trophy, which ensures its presence in future editions of the popular video game.
Having cared for the XNR for nearly three decades, the owner has now decided to part with the unique machine. It will be offered RM Auctions in their annual Monterey Sale on Saturday, August 18th. The estimate for the one-off Plymouth is available on request.
Article by Wouter Melissen, last updated on August 13, 2012
Add your comments on the Plymouth XNR