Six Volkswagen owners from Santa Barbara County have filed a class-action lawsuit against the German automaker’s U.S. manufacturer and distributor, claiming their vehicles have decreased in value following accusations that Volkswagen used software to cheat emission standards.

Federal and California environmental regulators recently accused Volkswagen of installing software in its Audi and Volkswagen diesel automobiles years 2009-2015 that turned on the full emissions controls only during emissions testing.

When the car was driven normally, the effectiveness of the emissions pollution control devices was reduced by up to 40 percent, the filing reads.

The claim is filed in Santa Barbara County Superior Court on behalf of all California drivers who own diesel Audio and Volkswagen cars from those years. The lawsuit is filed against Virginia-headquartered Volkswagen Group of America, the Santa Barbara car dealer Santa Barbara Volkswagen, Solazyme and Amyris.

San Francisco-based Solazyme and Emeryville-based Amyris partnered with Volkswagen to measure the environmental impacts of the TDI® Clean Diesel technology.

“We chose to file in California State Court here in Santa Barbara because there are California entities that VW worked with to ensure their emissions controls were meeting government standards,” said Leila Noël, partner of Cappello & Noël LLP, the Santa Barbara law firm filing the class action suit on behalf of class members. “We believe these entities along with the Volkswagen knew the numbers were rigged. We have limited our case to California. Most other firms are filing for a nationwide class.”

Noël estimates that approximately 50,000 Californians have purchased diesel Volkswagens with the defeat device.

The lawsuit is charging the defendants with fraudulent concealment, violation of California’s False Advertising Act and violations of California’s Unfair Competition Law.

A June Volkswagen news release stated that the two companies’ “initial analysis found that advanced renewable fuels in the test offered comparable performance to standard crude-based diesel fuel blends while producing less CO2 emissions on average.”

“Volkswagen made claims about these cars that they knew were untrue to entice people to buy,” Noël said. “Class members are now left with automobiles that are not only harming our environment, but are currently of little or no value.”

Volkswagen is the world’s largest automaker and the industry leader in diesel car sales in the United States, according to the filing. The U.S. Environmental Protection Agency said that the German automaker could face penalties of up to $18 billion.

Volkswagen shares have dropped nearly 20 percent since the announcement on Sept. 18.

Alex Kacik can be reached at akacik@pacbiztimes.com.