Infiniti’s bestseller — the midsize QX60 — receives a makeover this fall with an updated powertrain and more muscular styling.

The 2022 QX60 three-row crossover will be the first product launch since Nissan Motor Co. hatched greater collaboration between the mass-market Nissan and premium Infiniti brands.

Infiniti will share platforms, powertrains and assembly lines with Nissan to boost product development efficiencies. The second-generation QX60 will test whether the brands can share more components without sacrificing their distinct identities.

Updating the QX60 is a critical step in rejuvenating Infiniti, which has suffered multiyear sales declines in the U.S. In 2020, Infiniti deliveries slumped 32 percent — the largest annual drop in the brand’s history.

U.S. sales of the QX60 tallied 22,880 last year and accounted for 29 percent of Infiniti volume.

The QX60, along with the compact QX50, form the “backbone of Infiniti’s sales in the U.S., so executing the refresh is critical for the brand’s success,” said Tyson Jominy, vice president of the Power Information Network at J.D. Power.

The QX60 is one of the oldest products in the segment and needs to counter the recently upgraded Acura MDX, one of its top competitors, Jominy added.

The 2022 QX60 is powered by a 3.5-liter V-6 engine that delivers 295 horsepower.

The new model ditches a continuously variable transmission for a new nine-speed transmission that delivers improved acceleration and a smoother driving experience, Infiniti said.

The nine-speed transmission has a larger ratio spread — almost 10:1, said Dave Kiesel, manager of powertrain performance at Infiniti’s Arizona Testing Center.

“This gives the customer the ability to have a standing-start performance that is confident and responsive,” Kiesel noted. “The corollary of that is also that you maintain your fuel economy on the freeway.”

By launching with just one engine option, a gasoline V-6, Infiniti is aiming at the broadest part of the midsize-crossover segment, Jominy said. Last year, six-cylinder engines accounted for 70 percent of sales in the segment.

“It is surprising Infiniti did not choose to bring several powertrains to launch, as these will likely be required shortly to keep up with the competition,” Jominy said.

Jeff Pope, Infiniti Americas group vice president, left the door open for the possibility of other powertrains. “We will not rule out anything in the future,” Pope told Automotive News last fall.

Infiniti has not revealed design details of the new QX60, though it released camouflaged photos of the crossover undergoing road tests. The automaker teased elements of the next-generation crossover in a 2020 design study referred to as the QX60 Monograph.

The QX60 Monograph’s wide body and track revealed more muscular styling than the outgoing model. The design study featured a raised hood, sculpted shoulder line, larger grille, dual 12.3-inch screens and a two-tone roof.

In the front and rear, the Monograph features “digital piano key” lighting, while the rear lamps wrap around the back in a continuous swoop.

“This design execution, yes it’s for QX60, but it also lends itself to where we might go in the future,” Pope said about the design study.

“If you look at the Monograph that was shown, any vehicle that’s going to look like that is going to draw the attention of many consumers that have never driven Infiniti before,” he said. “Which is exactly what you want in a new model launch.”