Evidence like this letter continues to suggest top figures knew about the emissions problem. In addition, a separate Bild am Sonntag report recently claimed that an employee emailed Winterkorn in May 2014 to tell him US regulators could discover the cheating. In the lower echelons of the company, the deception was allegedly an open secret among engineers as early as 2006, and people kept quiet even after workers tried to admit what was happening.
This culture of secrecy seems to go even deeper than just the diesel emissions scandal. For example, engineers admitted that they cheated on CO2 tests to meet the company's strict standards. According to Green Car Reports, these problems also affected the US. In 2004, an Audi worker in America allegedly discovered an issue with the exhaust gas temperature sensor in some vehicles, but a German executive said not to admit the problem to US regulators.
It's not clear whether any high level employees tried to fix the diesel emissions issue or if they simply kept the problem hidden. The company's internal report, which is due in the latter half of April, might address that concern. So far, the VW Group has said only a small group of people caused the scandal. However, these many allegations to the contrary make that claim difficult to believe.