US sued Volkswagen over emissions scandal.

The US Justice Department has opened legal proceedings against Volkswagen (VW) over the scandal that saw the German car maker fit software that allowed millions of vehicles to cheat emission tests. Late on 4 January, a lawsuit claiming the beleaguered car manufacturer "violated" clean-air regulations was filed on behalf of the US Environmental Protection Agency (EPA) at a federal court in Detroit, Michigan.
"The complaint alleges that nearly 600,000 diesel engine
vehicles had illegal defeat devices installed that impair their emission control systems and cause emissions to exceed EPA's standards, resulting in harmful air pollution," said the filing.
According to the lawsuit, the car maker deliberately tampered with vehicles destined for the US market by fitting them with what the US regulators described as a "defeat device", software designed to cheat emission tests.
The devices were designed to keep diesel engines' emissions in the required range during testing before switching off in real-life driving conditions, to boost performance. That resulted in diesel engines producing greenhouse gas emissions 40 times greater than the federal standard.
Under US laws, car manufacturers are required to disclose such devices to the regulators. However, since VW kept the software secret, the regulatory filings allege the company's vehicles were sold without the required "certificate of conformity", which is issued by the EPA to regulate new cars produced or imported into the US.