Motor giant Volkswagen installed unlawful ‘defeat devices’ in thousands of diesel engines, the High Court has ruled in a key decision in proceedings brought on behalf of more than 90,000 UK customers.

In a judgment handed down today, Mr Justice Waksman ruled that software in a particular type of VW engine – used in VW, Audi, Skoda, and SEAT vehicles –  enabled the engine to recognise when it was being tested for compliance with EU vehicle emissions standards and reduced its NOx emissions accordingly. However, on the road, in normal driving conditions, that function was turned off and impermissible NOx levels were produced.

The Crossley & ors v Volkswagen Atkiengesellschaft & ors judgment, which covered two of the trial’s preliminary issues, said: ‘A software function which enables a vehicle to pass the test because (artificially) it operates the vehicle in a way which is bound to pass the test and in which it does not operate on the road is a fundamental subversion of the test and the objective behind it.

‘In other words, it destroys the utility of the test because it makes it impossible for performance under it to be the approximation of normal driving conditions and performance which it is intended to be.’

Waksman J added he was ‘far from alone in this conclusion', citing the German Federal Motor Transport Authority and ‘numerous courts’. The court must now determine the losses payable to the 91,000 UK claimants.

Leigh Day and Slater & Gordon represented the claimants. Leigh Day partner Bozena Michalowska-Howells said: ‘We hope that Volkswagen accepts the court’s decision and we urge them to now do the right thing and put their customers first by entering into settlement negotiations so that our clients are not forced to drag VW through the courts and be faced with further years of litigation to determine their losses.'

Gareth Pope, who leads the legal team at Slater and Gordon, added: ‘This damning judgment confirms what our clients have known for a long time, but which VW has refused to accept: namely that VW fitted defeat devices into millions of vehicles in the UK in order to cheat emissions tests.'

A spokesperson for Volkswagen Group said the company is ‘carefully considering’ grounds for appeal. ‘While Volkswagen is disappointed that the outcome was not in our favour, the judgment relates only to preliminary issues. To be clear, today’s decision does not determine liability or any issues of causation or loss for any of the causes of action claimed. These remain to be determined by the court as the case continues.

‘Volkswagen remains confident in our case that we are not liable to the claimants as alleged and the claimants did not suffer any loss. We will continue to defend our position robustly. Nothing in this decision today changes this. We look forward to making progress with defending the remainder of the case.

‘Volkswagen is considering carefully the grounds on which it may seek to appeal today’s decision.’