One-of-a-kind prototype: The 1949 Cadillac Coupe DeVille has something unusual under the hood

The Cadillac DeVille series was produced from 1959 to 2005. And not only is it the company's second-longest-running model (the Eldorado was sold for 49 years), it's also among the 20 longest-running American automobiles. But did you know that the DeVille was actually born ten years before its debut as a standalone model?

Cadillac began using the name in 1949. At the time, it was designated as a trim level for the Series 62. But looking beyond production models, the Coupe DeVille name was first introduced earlier that year on a one-off vehicle built for the inaugural GM Motorama.

Motorama, an auto show organized by General Motors, showcased concept cars, halo models, and emerging technologies. In 1949, the show featured 32 production and custom cars from each of GM's five divisions. Among them was the first-ever Coupe DeVille.

The hand-built prototype previewed the production model that would debut later that year and become the personal car of GM Chairman Charles Wilson. He kept the coupe until 1957, when he gave it to his secretary.

Presumed lost for decades, the prototype resurfaced in 2014 as a fully restored gem. The transformation was made possible by Cadillac collector Steve Plunkett, who purchased the vehicle in unrestored (but solid) condition in 2012. It’s been ten years since the prototype was put on display as a newly restored machine, and the coupe still shines as if it just rolled out of the shop.

Finished in dark gray with a silver roof, the Cadillac isn’t exactly striking at first glance, but it has a few unique features to boast about. Built on the bones of a 1948 convertible, the Motorama prototype features a longer wheelbase and elements that didn’t make it into the production model.

In addition to the 133-inch (3,378 mm) wheelbase, which is seven inches (178 mm) longer than the regular Coupe DeVille, the concept has extended rear fenders with faux vents and chrome moldings. The roof also looks different toward the rear (there's no sloping rear window) and incorporates additional chrome trim. I can't say it's radically different, but the Motorama concept looks a lot better than the production model that followed.

While both the exterior and interior are true to the 1949 car's specifications, things are a little different under the hood. According to Steve, the prototype lost its original 331-cubic-inch (5.4-liter) V8 engine sometime in the 1960s. The car was still with Wilson's former secretary, who asked GM for a replacement engine. The company agreed and sent her a 1957 Eldorado unit equipped with a similar 2×4 barrel carburetor setup.

And here’s where things get weird: GM stamped the block with the original 1949 VIN. This means that the prototype now has a matching-but-incorrect engine, one that was fully licensed by Cadillac. Now, that’s something you probably won’t find in another factory vehicle.

You can learn more about this fabulous prototype, the first vehicle to feature a one-piece curved windshield and side window defrosters, in the video below. It was featured on Lou Costabile’s YouTube channel, which you should definitely subscribe to if you’re into rare classic cars.