Ten years after the so-called 'dieselgate' scandal came to light, substantive hearings in group litigation on behalf of some 1.6 million car owners have begun in London. 

The Pan-NOx litigation case, before Lady Justice Cockerill, sitting as a judge in the High Court, opened in Court 76 of the Royal Courts of Justice this morning. It is listed to run for three months, with a further possible hearing to settle any financial redress, listed for next year. 

In the cases brought by lead firms Leigh Day and Pogust Goodhead, the court will hear allegations that five carmakers - Mercedes, Ford, Peugeot/Citroën, Renault and Nissan intentionally misled motorists by using unlawful software known as 'prohibited defeat devices' to cheat emissions tests. The care companies deny wrongdoing. 

In a statement this morning, Pogust Goodhead's chief executive Alicia Alinia said: 'This trial is a mammoth feat by the justice system, reflecting the scale of the alleged wrongdoing by car manufacturers. The court will test whether prohibited defeat devices were used to game emissions rules and, if so, what impact they have had on the air we all breathe and the health of people exposed to higher levels of harmful pollution.'