Volkswagen owners in the Sacramento area on Friday filed the latest in a series of class-action lawsuits against the automaker, alleging fraud, breach of warranty, unjust enrichment and negligent misrepresentation in response to VW's acknowledgement that its diesel engines were designed to defeat emissions testing. The lawsuit seeks class-action status on behalf of "tens of thousands" of Californians who bought or leased VWs with diesel engines from 2009 to 2015, the Sacramento Bee reported.

The German automaker already is facing fines of as much as $18 billion after admitting it used software that reported misleading emissions data during testing. “I personally am deeply sorry that we have broken the trust of our customers and the public,” said CEO Martin Winterkorn, who has since resigned, the first in what is expected to be a long line of exiting executives. “Volkswagen has ordered an external investigation of this matter.”

“Put simply,” the complaint alleges, “[Volkswagen’s] defeat device results in cars that meet emissions standards in the laboratory or testing station, but during everyday operation the device is programmed in such a manner that [a car] emits nitrogen oxides at up to 40 times the standard permitted by U.S. health regulations.” Nitrogen oxides contribute to ozone and smog.

The lawsuit, which was filed Friday, notes not only were VW buyers cheated out of the low-emissions vehicle they thought they were driving, the cars are now worth less money on trade-in. The suit seeks unspecified damages.

As many as 500,000 vehicles in the United States and 11 million worldwide could be involved, federal regulators have estimated. The complaint estimates 77,000 of them were sold in California.

Separately a pair of Stanford University teachers filed a similar suit in San Francisco Friday, the second in the Bay area, involving their 2013 Passat. A Los Angeles resident sued over his 2010 Audi. Other suits have been filed in Iowa, Missouri, Tennessee, Maine, Oregon, Wisconsin, Florida, Virginia, New York, North Carolina, Kentucky, Massachusetts, Georgia, Texas and Vermont, in addition to suits filed  consumer-rights law firm, Hagens Berman and Keller Rohrback of Seattle and Bailey & Glasser of Boston. Canadian VW owners also have filed suit.

Investigations into Volkswagen have been opened in several countries, including India and Norway.

The scandal has enraged VW owners, especially in light of a multimillion-dollar advertising campaign touting its clean diesel cars. Under enticing slogans like “no compromise,” the company spun a narrative that its cars offered both great performance and high fuel economy without the smoky emissions of traditional diesel vehicles.

“In an ideal world, I want them to show up at my door with a check for $27,000. I'd tell them, 'There’s the car, take it and good luck to you,' ” said Christopher Monroe of Ithaca, New York, who owns a 2010 Jetta.