After nearly 20 years as a loyal Volkswagen customer, Bob Merlis is among scores of Americans determined to get rid of their cars after the German automaker admitted it cheated in emission tests.

"I just feel completely betrayed," the elegant Californian in his 60s said as he sat at the wheel of a diesel-powered Jetta he bought two years ago.

"I was attracted to it because of the environmental aspect of it, being 'clean,'" he told AFP.

"You know, they say if it's too good to be true, it can't be true, and that's the case: to have a car with great mileage, and strong performance, and that meets our clean air standards."

According to US authorities, VW has admitted that it equipped about 482,000 cars in the United States with sophisticated software that covertly turns off pollution controls when the car is being driven.

It turns them on only when it detects that the vehicle is undergoing an emissions test.

With the so-called "defeat device" deactivated, the car can spew pollutant gases into the air, including nitrogen oxide, in amounts as much as 40 times higher than emissions standards, the US Environmental Protection Agency (EPA) said.

- 'Ruins the environment' -

"There's going to have to be a buyback campaign," Merlis told AFP.

"Because my concern is that if the car is adjusted so that emissions fall into line with the law, then the performance and the mileage isn't there, it is still not the car they sold us."

Grace Balangue says she is planning to trade her Volkswagen in for something more trustworthy, and less polluting.

"I can't drive a car that ruins the environment," she said as she filled her tank in Los Angeles.

Germany's powerful car industry has been reeling over the revelations that Volkswagen fitted up to 11 million of its diesel vehicles worldwide with devices capable of fooling emissions tests.

The scandal, which emerged last Friday when US officials publicly accused the company of cheating and launched a criminal probe, has now gone global with French and South Korean authorities also announcing investigations.

The deception is seen as particularly offensive in California, which has the nation's strictest emission standards in an effort to control the noxious smog that envelops Los Angeles.

"Oddly enough we just got it 'smogged', to make sure it was ok," said Marivi Badin.

"To find out all these games are being played, you know it is just disheartening."

Badin said she decided to spend thousands extra for a diesel rather than a gasoline engine because it was more fuel efficient and also promised to be "clean."

"When you spend this kind of money on an automobile and that is something that you need to take you to and from work or wherever, you're expecting it to perform at a certain level, and it's not. That's very disappointing."

- Owners file class-action lawsuits -

Volkswagen could face as much as $18 billion in environmental fines in the United States alone.

Lawyers have smelled blood.

The Seattle-based consumer rights firm Hagens Berman filed a class-action lawsuit hours after the scandal broke Friday.

The firm had received inquiries from more than 1,000 people in 20 states by Monday and expected to have suits filed in all 50 states by the end of the week.

"The half-a-million people who own these cars are furious, and with good reason," said managing partner Steve Berman.

"Not only did they pay more for something they never received, but they've been victim of a tremendous act of deception."

Rival Dan Mensher took to YouTube to urge Volkswagen owners to seek his help in suing the German carmaker.

"If you own one of those vehicles you probably wonder: What should I do?" he said in a video posted on YouTube by his firm, Keller Rohrback.

"If you are interested in understanding what your rights are, contact us."