The US government has formally sued Volkswagen over the emissions-cheating software that was found in nearly 600,000 vehicles sold in the country - exposing the company to potentially billions of dollars in fines.
The civil complaint against the German automaker, filed on behalf of the Environmental Protection Agency, alleges the company illegally installed software designed to make its “clean diesel” engines pass federal emissions standards while undergoing laboratory testing.
The vehicles then switched off those measures to boost performance in real-world driving conditions, spewing greenhouse gases at up to 40 times what is allowed under federal environmental standards, the Associated Press said.
“Car manufacturers that fail to properly certify their cars and that defeat emission control systems breach the public trust, endanger public health and disadvantage competitors,” said John Cruden, the assistant attorney general for the Justice Department's Environment and Natural Resources Division.
“The United States will pursue all appropriate remedies against Volkswagen to redress the violations of our nation's clean air laws alleged in the complaint.”
The company is in the midst of negotiating a massive mandatory recall with US regulators and potentially faces more than $18bn in fines for violations of the federal Clean Air Act.
The company and its executives could also still face separate criminal charges, while a raft of private class-action lawsuits filed by VW owners are pending.
Volkswagen Group of America spokeswoman Jeannine Ginivan said on Monday that the company “will continue to cooperate with all government agencies investigating these matters.”
The federal lawsuit alleges that Volkswagen intentionally tampered with the vehicles sold in the US to include what regulators call a “defeat device”, a mechanism specifically designed to game emissions tests. Under the law, automakers are required to disclose any such devices to regulators.
Because Volkswagen kept its suspect software secret, the lawsuit alleges the company's cars were sold without a valid “certificate of conformity” issued by EPA to regulate new cars manufactured or imported into the country.