Editorial: Did Volkswagen cheat?

If the accusations against Volkswagen hold up, Americans should be outraged at the company’s cynical and deliberate efforts to violate one of this country’s most important environmental laws.

On Friday, the federal Environmental Protection Agency accused the German automaker of outfitting nearly half a million VW and Audi diesel vehicles with illegal “defeat devices” designed to circumvent vehicle emissions tests. The devices were not installed by accident, oversight or errant design. According to the EPA’s description, VW’s actions were willful, and as a result these cars — from the 2009-15 model years — can each generate up to 40 times the maximum allowed emissions of nitrogen oxides, gases linked to smog and climate change. The EPA told VW it was “incumbent” upon the automaker to fix the problem, which likely means a recall. VW also faces a possible fine of up to $18 billion.

Why cheat? The EPA didn’t say, but automotive experts speculate that diesel engines that exceed emissions limits may have more power and better fuel efficiency. You know, the “zip” that VW likes to advertise and that helps sell cars. The certification tests in question are conducted by the EPA and the California Air Resources Board before automakers can sell specific models nationally and in California.

Rather than meet the standards, the EPA says VW sneaked in the defeat device software to detect when the car is hooked up to a dynamometer, a machine that measures emissions. When emissions are being measured, the defeat device tells the car to operate at “dyno calibration,” or full emission control levels, to meet the standards. At all other times, however, the software sets the engine to run on “road calibration,” allowing the excessive emissions. How can the program tell the difference? By noting the position of the steering wheel, variations in speed and other data that suggest no one is driving the car, and thus it is likely being tested.

The cheating came to light when the California Air Resources Board and the EPA pressed Volkswagen for an explanation for disparities found between lab tests and road tests of its vehicle emissions. The agencies didn’t find the technical reasons offered by VW to be convincing and said they would not issue certificates allowing 2016 models to be sold until the automaker offered an adequate explanation. “Only then did VW admit it had designed and installed a defeat device in these vehicles,” the EPA said. VW said it was cooperating with the investigation but otherwise had no comment.

Perhaps that’s out of shame. With humanity facing catastrophic damage from the effects of the greenhouse pollutants we pump into the air, VW’s transgression becomes all the more egregious.

Follow the Opinion section on Twitter @latimesopinion and Facebook