Concept Classic: 1960 Plymouth XNR – Exner’s Hot Slant-Six Corvette Fighter That Almost Got Built

Exner XNR fq

(first posted 8/3/2013)      Virgil Exner’s disappointment over his 1955 Chrysler Falcon two-seater not being green-lighted for production was deep and lasting. He loved sports cars, and was an enthusiastic and competent driver of them on the track as well as the road. In 1960, he and his team made another stab at a Corvette-fighter, this time based on the all-new 1960 Valiant. It clearly carried certain Valiant styling themes, and had a distinctive front end that would eventually get recycled. Its most unique aspect undoubtedly was its asymmetry, in an effort to capture the feel of the off-set “lay-down” Indy roadsters that were predominant in US circle racing at the time. And unlike the big DeSoto hemi V8 of the Falcon, the XNR stayed true to its Valiant roots: a hot Hyper-Pak 170 slant six is under its asymmetrical hood.

Exner XNR engine

Here it is, the most powerful American small six to date by far. Its output from 2.8 liters has been claimed to be 250hp, but that seems dubious. Nevertheless, the XNR was timed at 153 mph on the test track, and Exner himself took it to over 135. Hot stuff, especially for a six in 1960.

Exner XNR-concept-profile-1024x640

The KNR was based on the Valiant’s underpinnings, could have been built on the same lines, and was projected to sell for $3000, or about 25% less than a base Corvette. Undoubtedly, a production XNR would have had a more realistic windshield and possibly toned down a bit, but otherwise, the XNR was quite production-ready. Chrysler’s dysfunctional management at the time scuttled the plan after there was already considerable enthusiasm in the press.

Exner XNR rear

The XNR’s asymmetry is resolved in a dramatic cruciform “bumper”, and instead of the trademark “toilet seat”, there’s a very large fuel filler. Must have a saucer back there somehow…

Exner XNR fr

Needless to say, the XNR’s loop bumper foreshadows Chrysler’s infatuation with that on its “fuselage” cars starting in 1969. For that matter, the basic design concept that resulted in the production 1960 Valiant was being called “fuselage design” already then.

Ghia Assimetrica 001 1200

Like a number of other Ghia-built Exner one-offs, its builder tried to turn it into a limited production car for themselves. The Ghia Assimetrica was shown at a number of European car shows in order to find a sponsor or investor. The Assimetrica was of course toned down, with a real windshield and folding top, and a more conventional tail. In fact, this is undoubtedly closer to what a production Plymouth XNR would have looked like. No serious backers were found, but a small number were supposedly built, but none have survived.