When the redesigned Infiniti QX50 compact crossover launched in the spring of 2018, executives heralded it as the brand's most important product since the original Q45 luxury sedan three decades ago. The new crossover debuted a variable-compression engine that delivered V-6-like performance with four-cylinder diesel-like fuel economy.

Infiniti expected the QX50 to become the brand's top seller in the U.S. But that hasn't panned out, mostly because of launch snafus and quality problems.

QX50 sales through July were down 2.3 percent to 10,425 vehicles, putting the QX50 at the brand's No. 4 spot. Its best-selling model was the QX60 midsize crossover, at 25,695.

"We didn't do the perfect job of launching the car" with the right configurations, Christian Meunier, then-president of Infiniti, told Automotive News at the Shanghai auto show in April. "We realized that very quickly in the launch phase."

This year, Infiniti added a QX50 trim level the company said would make the model appeal to a wider market. The QX50 lineup now includes a $42,000 Luxe variant with a navigation system, a feature previously available only in the pricier Essential trim.

Infiniti dealer Mario Murgado said he is looking forward to new product.

Murgado, who owns Infiniti Stuart in Florida, expects the QX55 coupe to be a niche volume vehicle.

"If you sell 4,000 QX50s, maybe that's a car you sell a thousand of," he said.

Adding a coupe-like QX55 derivative is a low-investment way to bring new customers into the brand, said Ed Kim, analyst with AutoPacific.

"It offers a more style-driven counterpart to the QX50 that can potentially bring more conquest customers to Infiniti," Kim said. "As sales of Q50 and Q60 continue to shrink, Infiniti needs to backfill their lost volume with new and relevant products. QX50 is one step, and QX55 is yet another."

The QX55, like the QX50, will likely be assembled in Aguascalientes, Mexico, at the $1.4 billion joint-venture plant that is owned by parent Nissan Motor Co. and Daimler.