On May 17, 2006, an engineer in Volkswagen’s engine development department emailed colleagues about software borrowed from Audi. It ran one way during an emissions test cycle and another way the rest of the time. The engineer warned against using it in its current form. In the translation later filed in court: “This function is pure [cycle-beating] and can like this absolutely not be used for US’07.”
US’07 was the project to sell VW diesels in America, an important strategic goal for the company. The obstacle was nitrogen oxides, or NOx. New US limits, in full force from model year 2007, were significantly stricter than the old ones. In the Statement of Facts attached to its 2017 guilty plea, VW admitted that supervisors realized they could not build a diesel that would both meet those limits and attract enough American buyers.
So engineers built one that met them only on the test. The software recognized the published drive cycles regulators use on a dynamometer, a set of rollers in a lab. There it ran clean. On the road, it cut back the emissions controls.
Some engineers objected. In the fall of 2006, with their supervisors’ support, they took it to the head of VW brand engine development. At a meeting that November, according to the Statement of Facts, that supervisor decided to go ahead and instructed those in attendance, “in sum and substance, not to get caught.”
From model year 2009 the cars went on sale, marketed as “clean diesel.”
Around 2012, exhaust hardware on some of them began to fail. Engineers suspected the cheat itself: cars were staying in test mode too long on real roads. In July 2012 they explained it to two supervisors separately. Each told them to destroy the document they had used. Then the engineers improved the cheat. The new version also checked whether the steering wheel was turning, which it doesn’t on the rollers. Some engineers raised concerns again. In April 2013, the head of engine development approved it, and existing cars got it as a software update during servicing.
That same year, a team from West Virginia University, hired by the International Council on Clean Transportation, strapped portable emissions equipment to three diesel cars and drove them around California, one of them as far as Seattle. Two, which the EPA later identified as a 2012 Jetta and a 2013 Passat, emitted 5 to 35 times the US NOx standard, depending on the car and the route. On the California Air Resources Board’s rollers, both came in under it. The researchers wrote that their conclusions applied only to those three cars.
For over a year, VW blamed technical issues and unexpected real-world conditions. Inside VW, supervisors had chosen to hide the device while appearing to cooperate. What broke it was a certificate: regulators would not approve VW’s 2016 diesels until the gap was explained. On August 19, 2015, at a meeting with California regulators, a VW employee went against instructions from supervisors and told them the cars treated emissions differently on the rollers and on the road.
The EPA issued its Notice of Violation on September 18. Chief executive Martin Winterkorn said VW had “broken the trust of our customers and the public,” and resigned over the scandal. VW admitted that about 11 million cars worldwide had the software. In the US alone, the criminal and civil penalties and the two settlements announced by the Justice Department add up to about $20 billion.
One condition of the civil settlement: VW must test its own cars on the road, using the same type of portable equipment that caught it.