German prosecutors have commenced an investigation of Martin Winterkorn, the former CEO of Volkswagen, who resigned after reports that the company cheated on diesel emission tests in the United States. Since Winterkorn’s resignation, VW has been hit with dozens of class action lawsuits in the U.S. VW is alleged to have misled consumers by promoting “clean diesel” cars that actually emit up to 40 times the amount of acceptable limit of harmful emissions. In comparison to standard gasoline engines, diesel engines use less fuel and emit less carbon, but they also emit substantially greater amounts of nitrous oxides, which are known to impair health. VW’s crisis was triggered last week, when the U.S. Environmental Protection Agency alleged that the company employed sophisticated software that allowed vehicles to detect emissions testing and conceal nitrous oxide emissions to pass tests. Analysts have estimated that VW’s vehicles have emitted more than 40,000 tons of toxic gas in the U.S. per year, far exceeding the approximately 1,000 tons allowed by EPA standards. In the United States alone some 500,000 diesel vehicles contain such “defeat devices.” The company’s shares have fallen more than 35 percent since the scandal has emerged and it has set aside more than $7 billion to address claims.

Read more about this development here and here.

Read about the engineering behind VW’s software here.