Why now? That was the question I asked any General Motors representative who would listen at the reveal of the 2021 Chevrolet Tahoe and Suburban.

On Tuesday night, General Motors unveiled the larger, bolder, independent rear suspension-equipped 2021 Chevrolet Tahoe and Suburban in Detroit. Two gas engine options are carried over, though heavily updated from the current models, while a turbodiesel retrurns to the SUV siblings for the first time since 1999.

"Customers are asking for it," Tim Herrick, the new vice president of global product, told Motor Authority, noting it won't ever be the best-selling engine for the SUVs.

Chevrolet spokesman Monte Doran went further: "We have an engine that delivers the performance, refinement, and the efficiency that you need for this (application). You can't put a loud, slow, smelly diesel in a Tahoe or Suburban. It just doesn't work."

Herrick agreed. "They used to be smelly and oily, and no one liked it and you didn't want to stand by the pump. That stuff's kind of over with them," Herrick said, also noting the engine's refinement and the fact that it has come down in price.

Customers want a diesel for the fuel economy and power, specifically the torque, which the diesel engine provides early in the rev band. GM also benefits from the diesel's lower greenhouse gas emissions, which makes it "the first hammer to come out of the toolbox because it's good for that," said Herrick.

The turbodiesel will be "without question the fuel-efficiency leader for us for Tahoe and Suburban," but it's too early to talk fuel economy numbers, Doran said.

Doran also noted the turbodiesel was "developed concurrently" for both the pickups and the SUVs by the GM team in Turin, Italy, which develops all of GM's diesel engines.

The 3.0-liter turbodiesel inline-6 produces 277 horsepower and 477 pound-feet of torque. It first found a home in the 2019 Chevrolet Silverado 1500 and 2019 GMC Sierra 1500. It will be optional for the 2021 Tahoe and Suburban when they go on sale in the middle of next year and will be offered with rear- or four-wheel drive.