The trial is the latest chapter of what has become known as the "dieselgate" scandal, with the companies facing allegations they used illegal software to allow their cars to reduce emissions of harmful gases under test conditions. The court heard on Monday that car manufacturers decided they would "rather cheat than comply with the law" over vehicle emissions. The five carmakers - Mercedes, Ford, Peugeot/Citroën, Renault and Nissan - all deny the accusations.

Opening the trial, Thomas De La Mare KC, for the car owners, said that "each player in the industry basically took a conscious decision that customer convenience, which helped the industry sell more cars, was more important" than preventing pollution. In his written submissions, Mr De La Mare cited a report from the Centre for Research on Energy and Clean Air which found that excess nitrogen oxide - the emission created by diesel engines - had caused 124,000 premature deaths and 98,000 new cases of asthma in children in the UK and Europe between 2009 and 2024. But Alexander Antelme KC, for Renault, said in written submissions for trial that the allegation of cheating emissions tests was "without merit and untenable". "The features to which the claimants wrongly object are, in fact, appropriate and necessary elements of a well-designed diesel engine," he wrote. Neil Moody KC, for Ford, said in written submissions that the case was "scientifically illiterate" and "flawed on the facts and the law". "The inference seems to be of some sort of industry-wide conspiracy. The proposition need only be stated for it to be seen to be implausible." (BBC)