This is Concept We Forgot, Motor1's deep dive into weird and wonderful concept cars you might not remember.

Name: Cadillac Ciel
Debut: 2011 Pebble Beach Concours d’Elegance
Engine: Twin-Turbocharged 3.6-Liter V6 Hybrid
Output: 425 Horsepower
Drive Type: Rear-Wheel Drive

Four doors, four seats, 400 miles on the Pacific Coast Highway. That might as well have been Cadillac’s design theme for the Ciel convertible concept, which debuted at the 2011 Pebble Beach Concours d’Elegance with a softer, retro-tinged evolution of the company’s Art and Science design language.

Appropriate for its first public appearance in Monterey, the Ciel is “an open-air grand touring car inspired by the natural beauty of the California coast,” according to the Cadillac press release. Look no further than its gorgeous red paint, which is apparently inspired by the translucence of a glass of red wine held up to the sunlight – sure, whatever you say, Caddy. Glowing marketing-speak aside, this twin-turbocharged, hybridized, four-door convertible is a glorious look at what might have been.

2011 Cadillac Ciel Concept Exterior Doors Open
2011 Cadillac Ciel Concept Exterior Front Quarter
2011 Cadillac Ciel Concept Exterior Rear Quarter

The (Styling) Standard Of The World

Although clearly a member of the Cadillac family, the Ciel isn’t as edgy as the XLR or CTS that came before it. It retains the narrow, knife-slit headlights and taillamps of other Cadillacs, but instead of a crisp body-length shoulder that rises toward the rear, the Ciel looks a bit more nautical, with a character line that generates from the headlight before arcing down toward the doors. Another soft line appears above the bulging rear wheel arch, firming up as it cascades toward the trunk. The sharp front and rear fenders contrast with the distinctly barrel-shaped doors, distinguishing the Ciel from its slab-sided production siblings.

A boat-tail rear end recalls the 1967 Eldorado, especially combined with the sharp, vertical taillights, and it slopes toward the rear at the same time a nickel-plated strip on the rocker panel rises up. The concave front end is more like a pre-war luxury car than a modern Caddy, although its egg-crate grille and wreath-and-crest logo (RIP) are pure 2010s luxury. The light-pipe LED headlights have an icy finish and dovetail perfectly into the nickel-plated lower grille, which matches the art-deco vents on the front fenders and hood.

2011 Cadillac Ciel Concept Exterior Badge
2011 Cadillac Ciel Concept Exterior Mirror

Oddly, the polished windshield frame, wraparound front quarter glass, and rear headrest fairings look more like a Kennedy-era Lincoln than anything from GM’s luxury division; ditto the “French-style” doors. Still, those detail similarities do nothing to detract from what is a very brand-specific design: Remove the badges and you’d still know you were looking at a Caddy.

The Ciel rides on a long, 125.0-inch wheelbase, longer than the contemporary Escalade by 9 inches and only 5 inches shorter than the extended-length ESV. At 203.7 inches from bumper to bumper, it dwarfs the shorter ‘Slade by 1.2 inches, yet its overall height of 50.0 is a full lower to the ground. Unlike many of today’s “command-seating” sedans and coupes, the Ciel’s proportions were taken straight out of the 1960s, when long and low was the name of the game.

2011 Cadillac Ciel Concept Interior Front Seats

Midcentury. Modern.

As appealing as the exterior is, the Ciel’s cabin demands attention itself. The coach doors open wide – sans B-pillar – to provide access to an opulent four-seat cabin with a tone-on-tone design. Cadillac designers matched the leather-trimmed front and rear bucket seats to the exterior color, with saddle tan on the door panels, dashboard, and carpets. The Ciel’s interior also gets plenty of Italian olive wood trim, spanning the dash, full-length center console, front seatbacks, and steering wheel rim.

Cadillac mercifully resisted the temptation to festoon the cabin with screens and electronics. There are some nice concessions to technology, with Bluetooth connectivity and wireless charging for each passenger, but it’s all well hidden in the center console and seatbacks. Even the gauge cluster is understated, with transparent gauges that display information in a cascading front-to-rear format in order of importance.

2011 Cadillac Ciel Concept Interior Rear Seat Blankets

That doesn’t mean the Ciel doesn’t have some neat tricks up its sleeve, though they’re more of the analog variety, rather than digital. For example, if the three passengers get a little chilly, they can pull a leather tab to deploy a cashmere blanket over their shoulders. And the rear center console opens to reveal a humidor large enough for a few cigars. Each seat is heated and cooled – appropriate for the weather-variable drive from Santa Monica to Monterey – and has its own storage drawer stocked with sunblock, sunglasses, and towels.

Under The Hood

Powertrain and mechanical details are scant given its concept car status, but the Cadillac Ciel has a twin-turbocharged 3.6-liter V6 and hybrid powertrain, flexing GM’s then-new lithium-ion batteries for power density and efficiency. Cadillac claimed 425 horsepower and 430 pound-feet of torque for the Ciel, and it was able – theoretically speaking – of all-electric driving at low speeds.

All-wheel drive and carbon-ceramic brakes made an appearance, but the Ciel wasn’t intended for track duty. Chalk some of that more aggressive hardware up to show car dreams, rather than production reality.

2011 Cadillac Ciel Concept Exterior Wheel

Why Wasn’t It Built?

The Ciel was Cadillac’s first dalliance with a four-seat convertible since the departure of the soft-top Eldorado in 1985. It may have also been a water test for an ultra-luxurious flagship for the automaker, and rumors abounded that a Caddy with a then-staggering six-figure price was on the way to slot above the lame-duck STS and the $86,000 Escalade ESV Platinum.

Officially, the Ciel was “a pure concept and never intended for production,” according to company spokesperson Michael Albano, but some of its more graceful forms showed up on production cars, specifically the hood-stretching shape of the ATS’ headlamps. The spirit of a long and lean flagship also carried into the 2013 Elmiraj concept (another Pebble Beach debut) and the production CT6 sedan.

2011 Cadillac Ciel Concept Exterior Front Quarter
2011 Cadillac Ciel Concept Interior Dashboard
2011 Cadillac Ciel Concept Interior Doors Open

These days, Cadillac is hanging its flagship dreams on the $340,000 Celestiq EV, each unit of which will be customized to its owner’s tastes. Although rendered in four-door form, the long fastback Celestiq has a vintage charm of its own, although it hearkens to the 1930s, not the Ciel’s 1960s. Funnily enough, both cars’ names share some etymological roots – “celestial” comes from the ancient Greek word for heaven, while “ciel” is French for sky or heaven.

Where Is It Now?

Since its Monterey debut, the Ciel made the normal auto show rounds, including formal events in the tony Chelsea neighborhood of New York City and at Meadow Brook Hall in Rochester, Michigan. It even showed up alongside the plug-in hybrid ELR at the 2013 Beijing Motor Show.

Cadillac Ciel Gets A Starring Role in 'Entourage' Movie
2011 Cadillac Ciel Concept At 2013 Beijing Motor Show

The Ciel is a running, driving concept, and it even had a supporting vehicular role in the 2015 movie Entourage, a gift from agent Ari Gold to his prize client. Incidentally, the group drove a four-door, drop-top Continental in the original series, so the choice of a Cadillac for the movie must have been a shot across Lincoln’s bow.

These days, the Cadillac Ciel spends its time in a museum. “It is currently in our Heritage Collection and remains an important part of Cadillac’s history,” Albano told me. The Heritage Collection is currently closed to the public, so unfortunately, mere mortals don’t have access to the Ciel’s handsome looks. If that changes in the future, I want to be first in line to see it.

Gallery: 2011 Cadillac Ciel Concept

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