U.S. accuses Volkswagen of clean air violations

WASHINGTON (Reuters) - U.S. and California environmental regulators on Friday accused Volkswagen AG of deliberately circumventing clean air rules on nearly 500,000 diesel cars and the company could face penalties of up to $18 billion.

The U.S. Environmental Protection Agency alleged that Volkswagen used software in four-cylinder Volkswagen and Audi diesel cars from model years 2009 to 2015 to circumvent emissions testing of certain air pollutants.

"Put simply, these cars contained software that turns off emissions controls when driving normally and turns them on when the car is undergoing an emissions test," Cynthia Giles, an enforcement officer at the EPA, told reporters in a teleconference.

The feature, known as a "defeat device," results in the cars emitting as much as 40 times emissions allowed under clean air rules meant to ensure public health is protected, Giles said.

(Reporting by Timothy Gardner and Patrick Rucker in Washington and Bernie Woodall in Detroit; Editing by Eric Walsh and Matthew Lewis)