Image: The campaign group Mums for Lungs protesting outside the Royal Courts of Justice this year. Photograph: @CrispinHughes/Mums for Lungs/Crispin Hughes
On Monday 13 October 2025, the High Court will open proceedings in what has become one of the largest and most anticipated legal battles in modern British history. More than 1.6 million vehicle owners are bringing claims against some of the world’s biggest car manufacturers, accusing them of deliberately misleading consumers by fitting their diesel cars with “cheat devices” designed to falsify emissions tests. This is not just another corporate scandal — it’s a fight for truth, accountability, and justice on a massive scale.
At the heart of the case is the claim that manufacturers programmed their diesel vehicles to recognise when they were undergoing emissions testing. During these tests, the software would limit harmful nitrogen oxide (NOₓ) emissions, allowing the cars to appear far cleaner than they actually were. Once on the open road, however, the systems allegedly reverted to their normal settings, releasing pollutants many times higher than legal limits. For years, this deception has been linked to worsening air quality and public health impacts across the UK.
The High Court trial is expected to last three months, featuring evidence from scientists, software engineers, environmental experts, and company executives. It will scrutinise not only whether defeat devices were installed but also whether the manufacturers acted deliberately and what kind of losses consumers have suffered as a result. The case is being closely watched across Europe, as a ruling in favour of UK claimants could set a powerful precedent for future consumer and environmental litigation.
For the claimants, this trial represents the culmination of nearly a decade of waiting. Many bought diesel cars believing they were cleaner, more efficient, and environmentally friendly — only to learn that the promises were false. Now, they want compensation for the vehicles’ lost value, potential performance changes after recalls, and the betrayal of their trust. Most legal experts suggest that if the High Court finds in favour of the claimants, the damages could reach billions of pounds, making it one of the largest group compensation payouts in UK history.
There’s also a moral dimension to this case. Beyond the numbers, Dieselgate raises urgent questions about corporate ethics and the responsibility manufacturers owe to both their customers and the environment. As the High Court begins its hearings, it’s clear that this trial isn’t just about cars — it’s about whether global companies can continue to put profit ahead of honesty, and whether British consumers will finally see justice served.
What’s at stake in the High Court showdown
The Dieselgate trial opening on 13 October is a defining moment for how the UK handles large-scale consumer justice. The claim is being led by law firm Leigh Day alongside over twenty other firms in a coordinated group litigation order. Five major manufacturers — Mercedes-Benz, Ford, Renault, Nissan, and Peugeot/Citroën — have been selected as “lead defendants,” meaning their cases will be heard first. The court’s decisions on these lead cases will set the legal foundation for hundreds of thousands of others.
The central issue revolves around whether the alleged defeat devices were “prohibited” under EU and UK law, and whether the manufacturers knowingly misled customers. To prove this, lawyers for the claimants are expected to present internal documents, technical analyses, and witness testimony showing that the devices were designed to manipulate emissions testing. For the manufacturers, the stakes are equally high: losing the case could trigger not just financial penalties but long-lasting reputational damage.
The High Court has emphasised efficiency and transparency throughout the pre-trial process, managing complex evidence and strict disclosure deadlines. It’s one of the most logistically complicated group actions ever to take place in the UK, involving millions of documents, expert witness statements, and years of procedural wrangling. For those involved, the sheer scale of the case demonstrates the growing power of collective legal action in holding large corporations accountable.
If the court rules in favour of the claimants, the result could change how the automotive industry operates in Britain. Manufacturers may face stricter oversight, tougher regulations on vehicle testing, and greater consumer protection laws. A positive verdict for claimants would not only bring financial redress but also signal that corporate deception on this scale will no longer be tolerated.
At its core, this trial isn’t just about whether a few software codes crossed a legal line. It’s about a fundamental breach of trust between major car brands and millions of their customers. For years, the public was told diesel was clean, responsible, and part of a greener future. Now, that illusion has shattered — and the High Court’s decision will determine how the story ends.
Compensation: what’s possible — and what’s already been paid elsewhere
The big question for many affected drivers is simple: how much compensation could they receive? While the exact amount will depend on the court’s findings, previous settlements offer some clues. Claimants may be entitled to compensation for overpayment — the difference between what they paid for the vehicle and what it would have been worth if they’d known the truth — as well as losses in resale value and the potential cost of performance changes after emissions recall work.
The Dieselgate group actions are structured so that compensation will likely be calculated per vehicle. Those who owned multiple diesel cars during the affected period could receive payments for each one. The first phase of this High Court trial will focus on establishing liability — determining whether defeat devices were indeed installed and whether they were illegal. Once that’s proven, the second phase will address the “quantum,” or how much compensation is owed to claimants. This phase could begin in late 2026 or early 2027, depending on appeals and procedural outcomes.
If the claimants succeed, experts estimate that compensation could range from several hundred to several thousand pounds per vehicle. Some believe the total payout could exceed £5 billion across all claimants. Even though legal fees and deductions may reduce individual awards, a favourable judgment would still represent one of the largest consumer settlements in UK history.
Looking abroad, the scale of compensation paid elsewhere shows just how significant this case could be. In the United States, Volkswagen agreed to pay roughly US$10 billion to affected customers, plus additional billions in environmental penalties and buyback schemes. In Germany, the company faced a €1 billion fine, and similar settlements were reached in Australia and Canada. In 2024, Italian owners secured a €54 million settlement, with individual payouts of up to €1,100 per car.
The UK has been slower to act, with only one previous settlement — the Volkswagen case, which resolved in 2022 for £193 million shared between 91,000 claimants, averaging around £2,100 each before fees. However, the new High Court trial covers multiple manufacturers and millions more vehicles, suggesting the total compensation could dwarf that earlier figure. If successful, this case could finally put British diesel drivers on par with their global counterparts in terms of justice and redress.
Can you still join? How to get involved — before it’s too late
With the trial about to begin, many drivers are asking whether it’s still possible to join. The answer is yes — but time is running out.
If you owned a diesel vehicle between 2009 and 2020 from a manufacturer involved in the emissions scandal — including Mercedes, Ford, Renault, Nissan, or Peugeot/Citroën — it’s worth checking whether you qualify. Even if your car has been sold or scrapped, you may still be eligible for compensation based on ownership during the affected period. Many legal firms provide quick online eligibility checkers that can confirm this within minutes.
This moment marks a turning point for British consumers. Diesel owners have waited nearly ten years for their chance to hold carmakers accountable for misleading emissions claims. With the High Court trial now in motion, it’s not just about financial redress — it’s about justice, responsibility, and the principle that no company is above the law. If you haven’t yet joined, i strongly encourage you to check your eligibility today. A button will be available below to help you take that first step and become part of this historic case.
This trial is more than a courtroom event — it’s a national reckoning. After years of denials, delays, and settlements abroad, UK consumers finally have their day in court. For those who feel cheated and misled, this is the time to be heard. If your car was affected, don’t wait. Justice might have taken a decade to arrive, but it’s here — and it could be worth thousands.
