Press release
REVEALED: Around 500,000 more UK cars under suspicion for emissions cheating
18 September 2025
- Court documents reveal 23 more car models and engines allegedly fitted with emissions-cheating devices, representing over 500,000 vehicles estimated to remain on UK roads.
- A decade on from Dieselgate, millions of dirty diesels remain on Britain’s roads, pumping out toxic fumes linked to asthma, strokes and cancer.
- The Department for Transport is investigating 76 models but campaigners are calling on the government to expand their investigation to include these 23 additional models/engines to the extent that they are not already being looked at.
- ClientEarth and partner organisations are urging the government to expand investigations and make manufacturers, not drivers, pay for the clean-up.
Ten years to the day after the original Dieselgate scandal was exposed, car giants are once again under the spotlight.
In July, ClientEarth and Mums for Lungs successfully intervened in the ongoing Dieselgate consumer litigation in the High Court, where 1.9 million car owners are suing car manufacturers for allegedly using illegal emissions tech in their cars. ClientEarth and Mums for Lungs gained access to key information setting out the case against the manufacturers i.e. detailing the banned technology allegedly being used in the 21 sample vehicles at the heart of the trial. ClientEarth also previously obtained official German recall notices relating to two additional vehicle models/engines. According to analysis by the International Council on Clean Transportation (the organisation that helped break the original Dieselgate scandal), these 23 vehicle models/engines equate to more than 500,000 diesel cars estimated to remain on UK roads today. The manufacturers concerned are the five lead defendants in the ongoing UK court case.
Following a legal complaint from ClientEarth in March 2023, the Department for Transport has started investigations into vehicles suspected of using illegal emissions technology. However, despite the serious health impacts, it has still not published any findings or issued any recalls to fix the problem. It is currently investigating 76 vehicle models but refuses to say which ones. Members of the Healthy Air Coalition, ClientEarth, Asthma and Lung UK and Mums for Lungs are now demanding the government widen its probe or confirm that it is already investigating these vehicles and will take this additional evidence into account. This latest intervention could result in investigations being expanded to include up to 23 extra models and engines — representing around 500,000 vehicles estimated to be still in use on UK roads today and which might be recalled if found non-compliant.
Diesel vehicles fitted with defeat devices can pump out dangerous nitrogen dioxide at levels far above legal limits and are a major contributor to levels of the gas in the UK. Emissions from the likely use of defeat devices have been linked to 16,000 premature deaths and 30,000 new cases of asthma in children.
Campaigners warn that without stronger protections, scandals like Dieselgate will keep harming the public. They are calling for ambitious clean air laws to keep people safe, alongside urgent action to clean up the existing fleet of dirty diesel vehicles.
Emily Kearsey, ClientEarth lawyer, said: “Ten years on, it’s shocking that so many of these cars are still polluting our streets. We’ve seen no meaningful accountability yet despite a decade of evidence against car manufacturers. The government must act now and make polluters pay. The law is clear: if defeat devices are found, cars must be recalled and fixed and manufacturers, not drivers, must foot the bill. But until the government move forward with recalls, the British public remain at risk from excess emissions.”
Jemima Hartshorn, Founder Mums for Lungs, said: “I have heard from hundreds of parents in the past decade who are worried about air pollution. More than 120,000 children went to hospital struggling for their breath in London in 2024 alone. It is hard to bear the worry of children gasping for air, having to be in hospital instead of with their family at home or at school with their friends. Car companies built cars that emit illegal and toxic levels of gas and little lungs are paying for it every day. It is time the car manufacturers paid as well.”
Professor Nick Hopkinson, Medical Director of Asthma + Lung UK, said: “Dieselgate isn’t just a corporate scandal – it is helping to fuel a toxic air emergency that shortens the lives of tens of thousands of people in the UK every year. Diesel vehicles remain the biggest polluters on our roads, emitting ultra-fine particles that penetrate deep into people’s lungs. These can damage lung development, cause inflammation and trigger asthma and attacks of other respiratory conditions like chronic obstructive pulmonary disease (COPD). But it’s not just lung disease. The tiny toxic particles enter the bloodstream and reach vital organs like the heart and brain. The Government must act urgently to hold manufacturers accountable, set ambitious clean air targets, and bring UK air quality in line with World Health Organization guidelines.”
ENDS
Notes to editors:
Health impacts of diesel vehicles
Diesel tailpipe NOx emissions contribute significantly to poor air quality in many European cities.
On-road diesel vehicles were linked to 35,400 premature deaths in Europe in 2015, when the Dieselgate scandal first broke.
This year, the Centre for Research on Energy and Clean Air conducted a study looking specifically at the health impacts of excess emissions from vehicles likely to be using defeat devices. This found that in the UK these emissions have already caused an estimated 16,000 premature deaths and 30,000 new cases of asthma in children.
Additionally, the Health Effects Institute has found strong connections between traffic-related NO2 pollution and asthma onset in children and adults and acute lower respiratory infections in children.
Evidence from the International Council on Clean Transportation
The International Council on Clean Transportation (ICCT), is the organisation that helped expose the original Dieselgate scandal in September 2015. In 2023, the ICCT published a report finding that hundreds of vehicle models from across the auto-manufacturing industry are likely to be using prohibited defeat devices. The ICCT used its database of market statistics and its ROADMAP model to estimate that the 23 vehicle models/engines referred to in this Press Release equate to over 500,000 cars remaining on UK roads today. These figures, produced on 16 September 2025, are available on request.
Legal complaints
ClientEarth lawyers sent legal complaints to the Department for Transport in the UK in 2023. They relied on new laws that came into force in September 2020 requiring market surveillance authorities to carry out tests to assess whether vehicles on the road comply with vehicle standards, including rules prohibiting the use of defeat devices (Regulation (EU) 2018/858). The complaints highlighted evidence from the International Council on Clean Transportation suggesting that hundreds of vehicle models are likely to be using prohibited defeat devices. If vehicles are found not to comply following investigations, the law says authorities have to act without delay to force manufacturers take corrective action to address the problem. The law also says that authorities are obliged to force corrective action if vehicles are posing a serious threat to people’s health.
Consumer cases
1.9 million consumer claims are currently being pursed in the High Court against 18 major auto-manufacturers alleged to have used prohibited defeat devices. A ten-week technical trial against Mercedes, Ford, Nissan, Renault, and Peugeot/Citroen is due to commence in October 2025. In July 2025, ClientEarth and Mums for Lungs were successful in getting access to key information setting out the Claimants’ case about the prohibited defeat devices allegedly being used in the sample vehicles at the heart of the trial.
About ClientEarth
ClientEarth is a non-profit organisation that uses the law to create systemic change that protects the Earth for – and with – its inhabitants. We are tackling climate change, protecting nature and stopping pollution, with partners and citizens around the globe. We hold industry and governments to account and defend everyone’s right to a healthy world. ClientEarth teams in Europe, Asia and the USA work to shape, implement and enforce the law, to build a future for our planet in which people and nature can thrive together.