Volkswagen’s cheating scandal began in September when emissions data gathered from multiple studies of its vehicles found that additional emissions were present during road tests compared to lab tests. It was discovered that several of Volkswagen’s models contained software that switches to a low-emission compliant mode when it detects an ongoing emissions test. Consequently, multiple high-ranking Volkswagen officials have resigned, including the CEO Martin Winterkorn, and the value of the company’s shares dropped significantly since September.
On October 8, 2015, the head of Volkswagen America, Michael Horn, testified in a House of Representative’s hearing about the emissions scandal. Horn claimed that the use of the software was not a corporate decision, but rather something a few employees engineered. As a result, Volkswagen has begun firing or suspending top engineers involved with the diesel engine development.