Gullwing doors are a dramatic way to show off a spacious interior, but don't get too excited. When the 2018 Lincoln Navigator goes on sale next year, it will have conventional doors and continue to offer seating for as many as eight people.

But designers get to have fun and take artistic license with concepts. So Lincoln design chief David Woodhouse spent nine months making a long-wheelbase show car with only six seats, lots of personal space, and a calming nautical theme. And the SUV was fitted with two huge winged doors that open dramatically and three teakwood steps that invite passengers to climb aboard.

"I wanted to showcase the interior," Woodhouse said of the doors that open in a dramatic upward motion to reveal calming blue materials, a flowing instrument panel that spans the width of the SUV, and a total of seven screens, including one for each rear passenger to play games or stream movies.

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The doors and fold-down staircase, which Woodhouse called "a fantastic exaggeration," won't make it into production when Lincoln starts building the next-generation Navigator next year at the Kentucky Truck Plant in Louisville. And it will continue to seat seven or eight passengers and be offered in standard or long-wheelbase.

But the piano key controls for gear selection can easily be put into production. As can many of the screens, the instrument panel, and the uncluttered interior.

The concept adopts the new Lincoln logo mesh grille that is on the MKZ and the new Continental coming this fall. It is the new face of Lincoln, replacing the split-wing grille that was briefly the face of the brand. Because the SUV is so huge—it's the largest vehicle in the Lincoln lineup—Woodhouse added a second string of lights in the massive headlamps, so the signature lines are now in pairs. It is a design element that will be reserved for large vehicles, Woodhouse said. The wheels have a radial turbine-inspired motif.

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Another topic they won't discuss is the switch to an aluminum body and whether the SUV remains body-on-frame.

Ford spent $1.3 billion on a new body shop at the Kentucky Truck Plant that also builds the Ford F-Series Super Duty pickup trucks that switched to aluminum bodies for the 2017 model year. Ford is investing a further $600 million in the plant for the next-generation Ford Expedition and Lincoln Navigator.

Ford introduced the Navigator in 1997, creating the luxury truck market, and has curated a small but loyal following. The current Navigator got a freshening and a more efficient engine for the 2015 model year—a stopgap until the next generation debuts.

The engine continues to be the 3.5-liter, twin-turbocharged, direct-injection V-6, but engineers coaxed more horsepower out of it, from 380 horsepower to more than 400 horsepower now, said Kumar Galhotra, head of Lincoln.

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Executives are not talking transmissions, but the expectation is the six-speed gives way to Ford's new 10-speed automatic that is on the 2017 F-150 Raptor. Being a Lincoln, it will have the brand's continuously controlled damping to adjust the suspension for a smoother ride.

The Navigator will have automatic emergency braking to bring the vehicle to a full stop, 360-degree cameras, lane keeping assist, and other advanced safety systems, chief engineer Andrew Kernahan said.

The luxury full-size SUV segment accounts for about 170,000 annual sales in the U.S. and 420,000 globally, and Galhotra said the well-known Navigator nameplate has cultivated loyal customers. It also has the youngest buyers in the Lincoln showroom with an average age of 54.

The current Navigator does not offer an upscale Black Label model, but one will become available for the all-new SUV when it launches. Black Label is a roughly $6,000 upgrade to better materials in the vehicle and concierge-style treatment by the dealership with perks such as car detailing and special menus at select restaurants.