**Why the World’s Top Diesel Carmakers Are Facing a UK Trial**
*By Dwaipayan Roy | October 13, 2025, 01:32 PM*
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### What’s the Story?
In a landmark case unfolding at London’s High Court, some of the world’s leading automakers are being tried over allegations of using illegal “defeat devices” to cheat on diesel emissions tests. Representing 1.6 million claimants, lawyers accuse companies including Mercedes-Benz, Ford, Nissan, Renault, and Stellantis-owned brands Peugeot and Citroën of deliberately manipulating emissions systems.
This major lawsuit, considered one of the largest in English legal history, comes nearly a decade after the infamous Volkswagen “dieselgate” scandal that dramatically shook the automotive industry.
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### Accusations Against the Manufacturers
Claimants allege that these automakers equipped their diesel vehicles with unlawful “defeat devices.” These devices are said to detect when a vehicle is undergoing official emissions testing and adjust performance to meet legal limits. However, under normal driving conditions, emissions would purportedly exceed regulatory standards.
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### Defendants Reject the Allegations
The accused manufacturers have strongly denied the claims, describing them as fundamentally flawed. They also reject any comparison to the 2015 Volkswagen scandal, which led to billions in fines and compensation.
Mercedes-Benz, in particular, has defended its emission control systems, stating that their technology was both legally compliant and technically justified.
The trial will focus on examining a representative sample of diesel vehicles from the five manufacturers to determine whether prohibited defeat devices were indeed used.
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### Wider Implications of the Case
The outcome of this trial could have significant consequences for many similar claims pending against other automakers, including Stellantis-owned Vauxhall/Opel and BMW.
Martyn Day, a lawyer representing the claimants from the Leigh Day firm, commented that if the allegations are proven, it would reveal one of the most egregious breaches of corporate trust in modern times.
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### Previous Legal Precedents
This is not the first time London’s High Court has addressed the issue of defeat devices. In 2020, the court ruled against Volkswagen in a related case.
However, the current group of claims dwarfs the previous Volkswagen case in scale, with claimants’ lawyers estimating its total value at around £6 billion.
Additionally, these automakers are facing similar global lawsuits related to diesel vehicle emissions testing.
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**Stay tuned for updates as this pivotal case unfolds, potentially reshaping accountability within the diesel vehicle industry.**
https://www.newsbytesapp.com/news/auto/london-court-trial-begins-in-diesel-emissions-lawsuit/story