The testing was carried out in May, 2015.

Investors have taken Volkswagen to trial, pursuing €9.2 billion (£8.2 billion) in damages over the emissions scandal. 

Shares in the carmaker crashed around 40 percent after the group admitted it’s diesel technology emitted illegal levels of pollution.

Andreas Tilp, a lawyer for the plaintiffs, said in court: “VW should have told the market that they cheated.”

“We believe that VW should have told the market no later than June 2008 that they could not make the technology that they needed in the United States,” he added to the Braunschweig higher regional court.

The scandal, which was revealed in September 2015, has so far cost Volkswagen over €27.4 billion in penalties and fines. 

In a statement to the BBC, VW said that the “lawsuit is solely and exclusively about whether Volkswagen complied with its disclosure obligations toward shareholders and the capital markets”.

“This case is mainly about whether Volkswagen complied with its disclosure obligations to shareholders and the capital markets,” VW lawyer Markus Pfueller said in court. “We are convinced that this is the case.”

The trial involves 50 lawyers and was to be moved from the courthouse to a nearby conference centre due to a large amount of interest in the case.

Shares in Volkswagen (ETR: VOW3) are up 1.69 percent and trading at 138,38 (1328GMT).