General Motors and Mazda said they intend to continue their diesel efforts despite VW's problems. GM offers a diesel-powered Cruze compact and is set to launch diesel versions of its Chevrolet Colorado and GMC Canyon midsize pickups. Mazda is working on a diesel Mazda6.
And so far there's no indication Volkswagen's issue will affect sales of full-size, body-on-frame pickup trucks and SUVs with diesel engines, whose owners are mainly interested in torque, fuel economy and range.
"Pickup buyers are not in [diesel] for the environmental benefits," said Dan Edmunds, a technology analyst at Edmunds.com.
Moreover, some diesel crossovers may escape untainted by the VW mess. The BMW X5, for example, actually met the emissions requirements in the same tests that helped uncover the use of "defeat device" software in VW and Audi models with 2.0-liter diesel engines.
Still, U.S. sales of diesel-powered cars and crossovers are sure to drop precipitously in the coming months, if only because VW and Audi accounted for most of the sales. In 2014, 138,174 such vehicles were sold in the U.S., according to data compiled by hybridcars.com; 68 percent were VW and Audi models.
Some analysts think the damage to VW and Audi, the two brands that have worked hardest to sell Americans on "clean diesel," will drag down all players.
"The move against VW is going to act as a catalyst to speed up the fall in diesel market share in Europe and halt it in the U.S.," said Max Warburton, an automotive analyst at Sanford C. Bernstein & Co. in London. In fact, he predicts the VW fiasco "probably" signals the end of clean diesel.
"Regulators will now be much more conservative about what they permit and much tougher real-world tests may prove either too difficult -- or too expensive -- for diesel to meet," Warburton said.
And while VW and Audi are introducing new 2016 models that are supposed to hit emissions targets without the use of test-cheating software, they are likely to find many customers have all but turned their backs on diesel.
Take Kevin Helmich, a resident of Ann Arbor, Mich., and a sales executive at a renewable-energy company. In 2010, he bought an Audi A3, lured by its peppy ride, impressive fuel economy and Audi's pitch that it was a green car.
He was so enthralled that he eventually bought a diesel model from Mercedes-Benz a few years later. But now, he says, he's lost faith in Audi and Volkswagen. "I do feel kind of duped," Helmich said. "I'm disappointed I believed their marketing story."
He's thinking about replacing the A3 at some point, and another diesel is unlikely. "There are just a lot more options for all-electric or plug-ins now," he said.