Diesel cars have never been popular in the United States and hopes they could gain greater acceptance under tougher fuel economy standards are fading in the wake of the Volkswagen scandal.

Diesel, which is about 30 percent more efficient than gasoline, became popular in Europe after governments shifted tax policies in the 1990s in order to cut carbon emissions.

But it never really caught on with American consumers, who enjoy much lower fuel prices and were unwilling to pay thousands of extra dollars upfront for a diesel engine that would save them money over time.

Carmakers also struggled to meet stringent air quality requirements because diesel emits higher levels of smog-forming particulates.

But when Volkswagen and other German automakers started marketing "clean diesel" cars with very good mileage ratings, toughened US fuel efficiency standards seemed to offer an opportunity to boost diesel's market share.

It might have worked if regulators hadn't discovered in September that Volkswagen installed illegal software in 600,000 diesel cars in the United States -- and 11 million worldwide -- that intentionally subverted clean-air regulations.

Some analysts think the scandal will continue to consign diesel cars to a US market share of only about three percent for the foreseeable future.

"Hybrids will benefit from the fact that diesel will not grow," said Pierpaolo Cazzola, who works in the energy technology policy division at the International Energy Agency.

"The scandal is not just a negative for Volkswagen. It also has a negative aspect for diesel technology."

But Allen Schaeffer, executive director of the industry-backed Diesel Technology Forum, while conceding that diesel will be "dinged" in the near-term by VW, said diesel cars could still double or triple their US market share due to tougher US fuel economy requirements.

He notes that there will be 54 diesel models offered in the US in 2016, up 15 from last year, although most are niche products.

"Consumers are pretty smart and this is being recognized as a big problem for one company, and I don't think people are translating that into questions about diesel in general," Schaeffer said.

But Cars.com editor Joe Wiesenfelder said the outlook for diesel growth in the US is hazy because lower gasoline prices reduces consumer interest in fuel economy.

- Messy legacy -

The Volkswagen debacle is only the latest hurdle for a technology that has long struggled to approach anything like its uptake in Europe.

General Motors and other big US automakers made a significant push into diesel in the early 1980s due to high energy prices. But the effort soon died following horror stories about exploding engines and sudden stalls on crowded highways. The cars were also associated with pollution, noise and bad odors.

Later though Volkswagen introduced a fleet of sporty diesel sedans like the Jetta with peppy performance and superior fuel economy.

But the German automaker's ambitions hit a giant stumbling block in September, when US environmental regulators unearthed the emissions-cheating scandal.

The emissions cheat devices allowed VW to claims its cars had higher fuel efficiency than they would have had if the pollution controls met regulations.

Diesel will remain a "tough sell" in the US, in part because VW still hasn't laid out its plan for fixes, said Edmunds senior analyst Jessica Caldwell.

"That's going to hurt the technology more than anything because it seems as though there are a lot of questions and it's not easily fixable," she said.

Analysts say diesel can still make sense for larger vehicles such as pickups and tow trucks. Another niche is luxury cars, which usually run on premium gasoline, which is more expensive than diesel fuel.

Jaguar Land Rover is launching new luxury diesel models in the US, starting with the Range Rover and the Range Rover Sport, both unveiled just as the VW scandal broke in September.

"We aren't changing any of our plans," said Jaguar Land Rover spokesman Nathan Hoyt. "Our vehicles use different technology than Volkswagen did, so we're not overly concerned about what happened there."