Diesel Vehicles: Defeat Devices

Rupa Huq Excerpts

Wednesday 25th February 2026 Westminster Hall

[Dr Rupa Huq (Ealing Central and Acton) (Lab)]

I beg to move,

That this House has considered the matter of defeat devices in diesel vehicles.

It is a true pleasure to serve under your chairship, Ms Lewell.

It was over a decade ago that the automotive industry, and indeed the world, was rocked by dieselgate, the Volkswagen emissions scandal. The public were horrified to learn about how the trusted German car giant Volkswagen—the one that gave us the “Herbie” kids film franchise and those iconic circular badges that were so beloved of the Beastie Boys—had knowingly faked vehicle emissions tests via defeat devices. Those devices are software designed to alter a vehicle’s performance, falsify results and limit emissions during the regulatory testing period, only to switch to their true polluting selves when they are driven on open roads.

VW’s range of diesel compact cars had been marketed as a green alternative to petrol, but it was found that it had been knowingly cooking the books to the point that the US Environmental Protection Agency found VW’s top people guilty of conspiracy to defraud customers. Confidence was shattered, share prices nosedived, reputational damage was done, vehicles were recalled, fines were paid, heads rolled at the managerial level, and the once-encouraged diesel became discredited—its fate in London was finally sealed by the ultra low emission zone.

We were assured that lessons would be learned, yet despite the outlawing of defeat devices, the problem seems to be wider than originally thought. “Dieselgate 2: The Sequel” is proceeding very slowly through the courts. I think there are several cases. Multiple models and manufacturers are accused of the same thing: spewing out dangerous and excessive emissions due to cheat technology. Companies have been knowingly deceiving drivers. It feels a bit like match fixing to those of us of a certain age—Bruce Grobbelaar comes to mind. Consumers have been conned once again into believing that they were driving greener, cleaner diesel cars. Results have been rigged. It feels almost as if I cannot go on the internet now without some sort of pop-up advert rearing its head—“Have you driven a Mercedes, a Ford, a Nissan, a Renault, a Citroën or a Peugeot between X and Y years? If so, click here to see how much compensation you could get.” It is all a little bit like ambulance chasing, is it not?

[Jim Shannon (Strangford) (DUP)]

I commend the hon. Member for Ealing Central and Acton (Dr Huq) for bringing us this debate. She is right to say that this does not just happen in England; it happens across all of the United Kingdom of Great Britain and Northern Ireland. Vehicles registered in Northern Ireland in 2015 were among those fitted with illegal software during the Volkswagen emissions scandal. Enforcement action uncovered diesel lorries operating in Northern Ireland with illegal emissions-cheating hardware deliberately disabling pollution controls. For 17 years, our MOT system in Northern Ireland failed to test diesel emissions properly, allowing such vehicles to operate undetected for too long while damaging air quality and undermining trust in regulations. Does the hon. Lady agree that more must be done to close regulatory gaps, strengthen enforcement and ensure that defeat devices are fully eliminated from all our roads throughout the United Kingdom of Great Britain and Northern Ireland?

[Dr Huq]

The hon. Gentleman makes such an excellent point as he always does. It is an honour to be intervened on by him. As he said, this was done with intent all over the British Isles, in all our nations. He mentioned the VW scandal. As I say, there could be worse round the corner. Despite the outlawing of these defeat devices, VW could just be the tip of a very murky iceberg. As the hon. Gentleman pointed out, this is not just about the men in white coats in the laboratory getting their technical results. This is not a fringe issue: it affects all our constituents and has real life consequences. Air pollution is one of our most pressing environmental challenges. Noxious nitrogen oxide emissions can cause respiratory illness, cardiovascular disease and childhood asthma—even premature deaths, which have been quantified.

In London, the city where we are now and where I am an MP, the devastating human impact was tragically illustrated by the desperately sad case of Ella Adoo-Kissi-Debrah: dead at just nine years old. Hers was the first ever case in which the cause of death on the certificate was “pollution”. The family had lived by the south circular; the north circular is in my seat. Ella’s mum, Rosamund, has been such a tireless campaigner in pushing for Ella’s law. Mums for Lungs has also done great work, while Parent Power had a breakfast event this morning on the other side of the building.

Clean air is not a “nice to have”, but an essential. We would not force a kid to drink dirty water, yet we expect them to breathe toxic air. Sadiq Khan’s ultra low emission zone in this city has helped to clean London of dirty diesel, but we know that children in vulnerable communities are the most susceptible.

These cars were bought in good faith. Remember Gordon Brown’s 2001 Budget: in those days, buying a diesel vehicle was incentivised. It was seen as environmentally superior to petrol because of the miles per gallon; in those days, people were not looking at NOx, but more at carbon dioxide. In that year’s Budget, I think, the road tax—and certain things for company fleets—actually encouraged diesel.

The VW scandal was a genuine scandal, just like the others I have seen since I have been here such as the contaminated blood and Post Office scandals. In its aftermath, the market share of diesels in this country has fallen from 50% in 2014 to just 5% now. But the bigger dieselgate 2 is on the horizon. If defeat devices have dishonestly been fitted to vehicles and emitted pollutants at levels way beyond what is legal and what consumers were led to believe, that leaves huge holes in Government enforcement and regulatory credibility. This will have been poisoning people.

I have a range of questions for the Minister. Although these vehicles are not being sold new any more, figures from Mums for Lungs show that 7.5 million diesel cars—a quarter of all UK cars—are still on our roads. They are responsible for 30% of total NOx emissions. There are also the vans, buses, the HGVS—if we add all those up, we see that action must occur.

In autumn 2024, the Department for Transport confirmed that it is investigating the possible use of defeat device trickery by several manufacturers. Rather than delve into the lengthy legal proceedings today, I want to raise questions about that Government inquiry, which is at best sketchy and is bound up in public health and consumer protection. It all seems to be shrouded in secrecy. There is the prospect, here, of illegally high emissions and asthma being in the equation, so every moment the results are delayed puts more children’s lungs at risk. At a time when everyone wants growth, Mums for Lungs has calculated that the UK economy is losing: action on dieselgate is expected to cost our economy £36 billion in the next 14 years. There are many reasons why we should address this issue.

I am asking the Minister—my good, hon. Friend—to step up a gear. The sheer number of potential claimants in dieselgate 2—1.8 million cars, potentially—dwarfs the settlement that eventually came out of VWgate; that 2022 settlement compensated only 91,000 consumers. This latest issue affects every constituency in the nation—including yours, Ms Lewell.

I have some questions: what is the status of the Department’s investigation? What is the timeline for its commencement? Where is it now? When will it conclude? What teeth does it have—i.e. what are the enforcement powers that the Department is prepared to deploy in cases of non-compliance? The Environment Act 2021 strengthened the Government’s ability to require manufacturers to recall vehicles where there are reasonable grounds to believe that they do not meet applicable environmental standards. Is the Department prepared to use those powers when appropriate? Where does the Driver and Vehicle Standards Agency fit into that process? What happens to vehicles currently on UK roads if they are found to be emitting unlawfully high levels of pollutants? Will the Government consider requiring their temporary suspension from use until they are brought into compliance? Could they have a little bit of tinkering and be okay?

According to one report from an international climate think-tank, excess emissions may already lead to 16,000 premature deaths in the UK and 30,000 new cases of childhood asthma. Overnight, Mums for Lungs sent me a whole load of new figures that I have not entirely processed, but which I can pass on to the Minister. If manufacturers are found to have breached the rules, who bears the financial burden of remedial action? Surely not the consumers who bought these vehicles in good faith. They thought that they were doing the right thing and believed that they were compliant. How do the Government intend to safeguard public health in the interim?

In 2016, the Tory Government launched an inquiry into the use of defeat devices by VW, but ultimately, they did not prosecute. The Transport Committee at the time expressed concerns about the Department for Transport’s “ambivalence” towards VW’s use of defeat devices. It described the Department as being

“too slow to assess the use of its powers”.

In other words, it was asleep at the wheel. This Minister is different from that former Minister, and I am sure that he will not repeat the mistakes of the last Tory Government.

There is now a second chance. The DFT should clearly prioritise the interests of the public and consumers in its current investigation. A decade after we were duped over diesel in the first emissions scandal, the public should not be left wondering whether enforcement powers will be used if wrongdoing is found. Court proceedings can take forever, but we must have assurances of urgency, transparency and consequence in the Government’s investigation, which is within their control.

Communities deserve clean air and consumers deserve honesty and protection. I am no Jeremy Clarkson. I cycle more than I drive, but I do both, and I take public transport every weekday. I find that it is difficult to know what is best and it can be bewildering—what is up or down and what is happening. The goalposts are constantly changing. What is it that is demonised? First it was petrol, then it was diesel. Now they have both been overtaken by electric, which is what we should all be using. I am pleased to see the roll-out of the Enviro400 and Enviro500 buses in London. However, for the average consumer it can be bewildering when the advice keeps changing and it can then feel a bit punitive.

Environmental standards must mean what they say. If they are breached there must be proportionate and decisive action. For far too long, motor manufacturers in the UK have victimised the public. They have misled consumers about pollution emitted by diesel engines, and they have put millions of citizens at risk simply because they live or work near roads. VW recovered its reputation to some extent. Certainly, on the Nextdoor app, people are still complaining that its badges are being nicked from the front of their cars. Whoever is doing that, can they stop? It is completely unnecessary to remove the circular VW logo.

These companies should come clean and make things right with those who they have harmed. The Government should do everything in their power to ensure that the public are in the driving seat. We should not have to wait for dieselgate 3.

[The Parliamentary Under-Secretary of State for Transport (Simon Lightwood)]

It is a pleasure to see you, Ms Lewell—my favourite sand dancer—chairing the debate this morning. I congratulate my hon. Friend the Member for Ealing Central and Acton (Dr Huq) on securing this debate on defeat devices in diesel vehicles. This is an important subject that rightly attracts scrutiny from Parliament, the public and campaigners. I acknowledge the concerns that my hon. Friend set out in her parliamentary questions and recent public commentary, which reflect the strength of feeling about this issue and the need for transparency and accountability from both manufacturers and regulators. Those concerns are entirely legitimate, and I welcome the opportunity to set out clearly how they align with the Government’s determination to uphold emissions standards and to ensure that the public can have full confidence in the environmental performance of vehicles on our roads.

I begin by reaffirming this Government’s commitment to delivering greener, cleaner transport and to reducing harmful emissions that affect communities across the country. Road transport emissions have significant implications for public health. We continue to take firm, evidence-based action wherever practices risk undermining public trust or air quality. Alongside our compliance and enforcement work, we are delivering wider measures to cut harmful emissions, including by supporting the transition to zero-emission vehicles, as my hon. Friend referenced.

We have consistently said that prohibited defeat devices are illegal, are misleading for drivers and can have negative impacts on the public. My Department has considerably strengthened its oversight of vehicle emissions in recent years. Since 2016, the Driver and Vehicle Standards Agency’s vehicle market surveillance unit has carried out increasingly rigorous emissions testing programmes using both laboratory and real-world methods to identify suspicious performance. The DVSA actively investigates potential non-compliance, and where its assessments identify issues, manufacturers are required to take corrective action in line with DVSA’s published enforcement policy.

This Government are undertaking a targeted and comprehensive programme of assessments, which formally commenced in early 2025, to assess a range of Euro 5 and Euro 6 diesel cars and vans produced between 2010 and 2018. As my hon. Friend would probably expect, we are focusing on vehicles with the greatest potential to cause harm, and our remediation actions are designed to reduce real-world emissions as quickly and effectively as possible. Although those models are no longer entering the market, they remain on our roads and the public quite rightly expect them to meet the standards set out at approval. I think, at present, there are 110 individual vehicle models that are under active investigation. That reflects the scale and complexity of the challenge.

To be absolutely clear, every vehicle model within scope will undergo a full assessment, and manufacturers are now working to firm, defined deadlines. The DVSA has completed assessments on a number of models and is now reviewing detailed submissions from manufacturers, with further assessments underway. We will conclude the process as soon as evidence allows, to ensure that any findings are robust, fair and accountable. Where non-compliance is identified, manufacturers will be required to take corrective action and enforcement will escalate where deadlines are not met. That approach is intended to achieve real-world improvements in air quality swiftly and fairly.

The Government have also strengthened the enforcement framework available to regulators. Since 2018, it has been an offence to place vehicles containing prohibited defeat systems on the market. My Department is equipped to require swift corrective action to address non-compliance. We are also considering whether we need to go further and build on our existing powers under assimilated EU law to require compulsory environmental recalls to deliver the intended outcomes.

Let me be clear: if non-compliance is confirmed, the DVSA will require manufacturers to take whatever remedial action is necessary, at no cost to consumers. Where any serious risk is evidenced, that remedial action must be taken without delay.

On transparency, I fully recognise the public interest in understanding the outcomes of this work, and manufacturer-specific findings will be published once investigations are complete and decisions are final. That approach is entirely consistent with other market surveillance activity. Waiting until that point is important to ensure that due process is followed, to avoid prejudicing live investigations and to maintain the integrity of any future enforcement action.

[Dr Huq]

I like what I have heard so far because, up to now, this has all been a bit mysterious. I wonder if it might be a good idea for me to meet the Minister. As a London MP, I have experience with ULEZ—we have a riding school in my seat, and an exemption was made for a horsebox. As I have experience of what happens in London, it would be good to talk this through, but it is impossible in a debate like this. Would the Minister meet me at some point?

[Simon Lightwood]

How could I refuse? Of course I will meet my hon. Friend.

Publishing incomplete or provisional findings would risk misleading consumers and compromising the quality of the technical assessments underway, as my hon. Friend will appreciate. To support transparency, I am pleased to say that the Department will shortly publish its dedicated gov.uk landing page. That will bring together all the emissions compliance publications, and once investigations are concluded, the final outcomes of the programme will be added to that page for full public access.

The programme has been developed in close collaboration with the Department for Business and Trade, the Department for Environment, Food and Rural Affairs and the UK Health Security Agency. That ensures that our approach draws on the full breadth of Government expertise. That collective effort means that our response is co-ordinated and informed by those who play a direct role in delivering cleaner, safer vehicles.

We are closely following the Pan-NOx group litigation concerning alleged defeat devices. Once the court hands down its judgment, we will consider carefully any implications, including whether changes are needed to our policy framework or enforcement approach. Internationally, we continue to work closely with regulators in EU member states, which helps us to anticipate emerging issues, align on best practice and ensure that manufacturers face a coherent regulatory environment across markets. It reinforces our ability to act decisively where cross-border issues arise, recognising that emissions compliance is a global challenge.

To conclude, a great deal has been achieved, and more is underway. The Government are delivering a thorough and proportionate programme designed to address potential non-compliance swiftly, transparently and in line with our legal duties. Our shared objective is clear: deliver cleaner air, protect public health, uphold public confidence and ensure that the vehicles on our roads meet the standards that the public expect and deserve.

Question put and agreed to.