The redesigned 2018 Lexus LS sedan gets a coupelike silhouette and a new twin-turbo 3.5-liter V-6 engine. Photo credit: REUTERS

DETROIT — Lexus is reinterpreting the flagship vehicle that launched the brand 28 years ago, fitting the redesigned LS sedan with a new twin-turbo 3.5-liter V-6 engine tuned to hurl the luxury boat from 0 to 60 mph in about 4.5 seconds.

The 2018 LS, unveiled Monday at the Detroit auto show, shares a platform with Lexus’ new LC 500 halo sports car, and gets more angular exterior features, a coupelike silhouette and an interior inspired by Japanese hospitality.

The update comes amid a downturn for luxury sedans and a broader shift across the market toward crossovers. Lexus sold just 5,514 LS sedans in the U.S. last year, down 23 percent and lagging far behind the Mercedes-Benz S class and BMW 7 series.

Nonetheless, Lexus executives see the redesigned LS as an important symbol of the brand’s ambitions to break out of its conservative mold and challenge the dominance of European brands in the upper tier of luxury.

“To create the all-new LS, Lexus took the approach of starting from new, reimagining what a flagship sedan should be, as if launching the brand all over again,” the company said. “The goal was not to improve on what Lexus has done, but to exceed expectations of global luxury customers.”

Longer, lower

The fifth-generation LS is longer and lower than the current model, using an extended version of Toyota’s new global architecture for luxury vehicles, dubbed GA-L.

Lexus said the new sedan strikes a difficult balance between greater handling agility and comfort. It does that through an active suspension system that uses braking, steering, powertrain and suspension to adjust to different driving conditions.

Engineers shaved 200 pounds from the current LS platform and body and mated its new turbocharged engine to a quick-shifting 10-speed transmission that powers the sedan to 60 mph in about 4.5 seconds, Lexus said. The new engine, rated at 415 hp, allows the LS to deliver power similar to an eight-cylinder engine while improving fuel economy and minimizing noise and vibration.

The current-generation LS is powered by a 4.6-liter V-8 that generates 386 hp.

Despite thin sales in a shrinking segment, Lexus sees the LS as critical to its lineup.

“The LS is the flagship of the Lexus brand,” chief designer Kouichi Suga said. “More than any other model, it embodies the history and image of Lexus and serves as a symbol for everything the brand stands for.”

Although a traditional three-box sedan, the LS has the silhouette of a four-door coupe that Lexus believes holds strong appeal for younger luxury customers, the company said.

It comes with a special rendition of the massive spindle grille with a texture that Lexus says “seemingly changes in different light.”

Inside, Lexus created a sumptuous interior with details such as 28-way power front seats that feature heating, cooling and massage and interior lighting inspired by Japanese lanterns. The choices of wood patterns for the interior trim include Art Wood Organic, Art Wood Herringbone and Gray Sapele Wood with Aluminum.

The LS will go on sale in the U.S. near the end of 2017.