The Federal Trade Commission has filed suit in California federal court against Volkswagen Group of America, seeking compensation for consumers who were deceived by the automaker’s “Clean Diesel” advertising as it cheated on government emissions tests.

The cheating occurred on VW and Audi diesel vehicles consumers purchased from late 2008 through late 2015. The automaker has admitted that it deliberately equipped the cars with a “defeat device” that would enable them to pass emissions tests even as they spewed nitrogen oxides at up to 40 times the legal limit (pdf).

VW marketed the 550,000 diesel vehicles sold in the U.S. as environmentally friendly and placed a premium price on them.

The campaign slogans included claims that the VW Jetta diesel “reduces nitrogen oxide (NOx) emissions by up to 90 percent,” and that the Audi TDI engines emit "fewer NOx emissions than comparable gasoline engines," and “meet the strictest EPA standards in the U.S.” The campaign also said that such clean vehicles would have strong resale values.

According to the FTC complaint, Volkswagen promoted its supposedly “clean” cars through a high-profile marketing campaign that included Super Bowl ads, online social media campaigns, and print advertising, often targeting “environmentally conscious” consumers.

The crux of the suit states that, because of the emissions-defeat device, VW claims about low emissions, nitrogen oxides reductions, emissions compliance, eco-consciousness, and comparative resale value were false or deceptive. As a result, consumers didn't get the benefit of the environmentally friendly car they thought they were purchasing, and resale values likely will fall. (Nitrogen oxide contributes to smog, acid rain, water quality deterioration, childhood asthma, respiratory ailments, and premature death, according to the Environmental Protection Agency.)

Audi labels cars are clean diesels

The company said in a statement, “Volkswagen has received the complaint and continues to cooperate with all relevant U.S. regulators, including the Federal Trade Commission. Our most important priority is to find a solution to the diesel emissions matter and earn back the trust of our customers and dealers as we build a better company.”

VW has yet to gain approval for a proposed fix to the affected vehicles.

In October, Consumer Reports pointed out that VW was happy to brag in its publicity efforts about real-world fuel-economy benefits that appear to be a result of the defeat device. We felt that using these claims in advertising was a concern and shared this information with the FTC.

William Wallace, policy analyst with Consumers Union, the policy and advocacy arm of Consumer Reports, said “We’re pleased to see the FTC take action as part of the government’s effort to hold Volkswagen accountable.”

"VW cheated consumers by aggressively promoting 'clean diesel' cars that actually polluted at a rate of up to 40 times the legal limit, and consumers deserve to be compensated,” Wallace added. “We urge government agencies and the court to reach a strong resolution that brings the cars into compliance with emissions standards, offsets environmental damage, and makes consumers whole."

The suit—filed in U.S. District Court for the Northern District of California, San Francisco Division—also seeks an injunction to prevent Volkswagen from engaging in this type of conduct again. It follows actions by the EPA and Department of Justice against VW for violations of the Clean Air Act.

The affected vehicles include 2009 through 2015 Volkswagen TDI diesel models of Jettas, Passats, and Touareg SUVs, as well as Audi TDI models.