Winterkorn indictment

The indictment against Dr Winterkorn goes considerably further - suggesting that the CEO himself was made well aware of what the engineers were doing and authorised a continued cover-up.

It claims that in early 2014, engineers heard about a study commissioned by the International Council on Clean Transport, which showed that VW diesels were producing far higher emissions on the road than in official lab tests.

It says that senior managers were informed, and warned that the study might result in VW's deception being uncovered. A memorandum was written for Dr Winterkorn explaining that the company would be unable to explain the test results to the authorities.

Volkswagen did admit some time ago that a memo was sent to Dr Winterkorn about the ICCT study, but claimed it was sent as part of his "extensive weekend mail", and couldn't say whether or not he actually took note of it.

The indictment goes on to claim that a group of senior engineers set up a task force to deal with official enquiries. It says they "pursued a strategy of concealing the defeat device in responding to questions from US regulators, while appearing to cooperate".

The most damning allegation against Dr Winterkorn, though, is that in late July 2015 he was given a detailed briefing about the situation in the United States - more than a month before the company admitted wrongdoing.

This, the document says, included a PowerPoint presentation to provide him with "a clear picture of how VW was deceiving US regulators … and the potential consequences of being caught".