The Volkswagen emissions scandal became public on September 18, 2015, when the U.S. Environmental Protection Agency issued the automaker a Clean Air Act violation notice. Volkswagen had installed engine-management software known as a defeat device in approximately 11 million turbocharged direct-injection diesel vehicles worldwide, including about 482,000 sold in the United States from model years 2009 through 2015. The software detected laboratory testing conditions and activated emissions controls, while ordinary driving produced nitrogen-oxide emissions as much as 40 times the U.S. legal limit. Volkswagen had marketed the vehicles as environmentally responsible and received green-car subsidies and tax benefits tied to their apparent compliance.
The deception was uncovered after the International Council on Clean Transportation commissioned West Virginia University researchers to conduct portable, on-road testing in 2013. Their results, published and reported to U.S. regulators in May 2014, showed Volkswagen Jetta emissions exceeding legal limits by factors of 15 to 35 and Passat emissions by factors of 5 to 20. After regulators confronted the company, Volkswagen acknowledged the manipulation in September 2015. CEO Martin Winterkorn resigned, and several senior engineering executives were suspended. Volkswagen agreed in June 2016 to pay up to $14.7 billion in U.S. civil settlements, pleaded guilty to criminal charges in January 2017, and was ordered to pay a $2.8 billion criminal fine in April 2017. By June 2020, the scandal had cost the company approximately $33.3 billion in fines, settlements, buybacks, and penalties; Winterkorn was charged with fraud and conspiracy in the United States on May 3, 2018.