The document summarizes the Volkswagen emissions scandal known as "Dieselgate". It describes how Volkswagen installed defeat device software in diesel vehicles that could detect when they were being tested and change the performance to improve results. When not in test mode, the vehicles emitted nitrogen oxide well above legal limits. The scandal affected millions of Volkswagen, Audi and Porsche vehicles worldwide. It resulted in major financial costs for Volkswagen, numerous lawsuits, and the resignation of top executives. The long-term impacts on Volkswagen's brand reputation and diesel vehicle sales also remain unclear.