In cases like these, the first questions to always ask are: What do the regulations say, and what’s in the cars?
The “Pan-NOx” litigation, as it became known, was England’s version of “Dieselgate.”
In 2023, a total of 13 group litigation orders against most of the world’s major car manufacturers were consolidated by the High Court in London.
The latest step was the prohibited defeat device (PDD) trial, heard by Lady Justice Cockerill between October and December 2025. It was billed as a “legal issues trial” and judgment was handed down on July 10, 2026.
All That Time, Effort and Expense, for What?
This was a monumental effort:
- 1,200 pages of written openings
- 2,000 pages of closing submissions
- 9,000 footnotes
- 10,000 pages of expert reports (excluding exhibits)
- 300 pages in the judgment
- 23 barristers from one set of chambers alone, Henderson Chambers
But to what end?
Lady Justice Cockerill adopted a narrow, purpose-based construction of “defeat device.” The result, in her own words, is that “the ambit of the claim is much reduced.” For an exercise mounted on behalf of roughly 1.6 million claims, that is quite the anticlimax.
The Ford, Renault and Nissan claimants discovered that their cars were innocent.
The Mercedes and Peugeot/Citroën/DS (PCD) claimants discovered that their cars had infringing devices. But the claimants didn’t get any damages, just the possibility of damages, and then only if they clear a future quantum hurdle and survive any appeals.
What’s in the Cars?
In cases like these, the first questions to always ask are: What do the regulations say, and what’s in the cars? That’s what this trial was about.
The trial assessed 20 agreed “core sample vehicles” drawn from Mercedes, Ford, Renault, Nissan and PCD. The scope was to decide:
- Whether those vehicles contained PDDs under the EU Emissions Regulation; and if so
- Whether any such devices could support a private law claim.
The judgment binds every party across all 13 group litigation orders, both participants and nonparticipants alike. It didn’t deal with quantum, which is set for a separate trial in October 2026, and it is all subject to appeals, which are likely.
The claimants’ big theory was that, to meet the regulations, emissions performance should barely differ in or out of the test. That was rejected by the court, which found that claimants must prove an intentional or impermissible purpose of causing the car to operate differently when it recognizes the emissions test cycle.
No such device was found in any sampled Ford, Renault or Nissan vehicle. The court did find that various Mercedes vehicles contained a coolant temperature sensor device, and that various PCD vehicles contained a split-injection device. On those bases, both brands failed the “intentional” test.
The judgment noted that narrow construction of “defeat device” is likely to be appealed, so it went on to ask what the outcome would have been if a broader test applied. Those fallback findings preserve a road map for any appeal, but they are not the operative result today.
What Is Winning Worth?
How much can those with the possibility of damages hope for? Nobody knows. There are hints in the judgment that the claimants’ will argue that a compliant vehicle “will cost more than these cars did.”
In other words, those claimants will run an overpayment approach. Even if the court were to accept that theory, and there’s no reason it should, this still would not resolve quantum. Take two decade-old diesels—one “clean,” one not. Suppose you compare the values when new, as the claimants would argue. But how would you do that?
After all this, the claimants now fall into two buckets. Those who will get nothing, and those may get something one day, or maybe not.
Some Automakers Vindicated, All Financially Burdened
Whilst most of the manufacturers can claim vindication on the central legal question (at least for now), what none of them can claim is that the exercise came cheap. Years of sample-vehicle testing, expert evidence, lawyers and court time do not come free.
But who ultimately pays for all this? That is all for a future argument about costs. Renault, for one, has already signaled publicly that it intends to pursue recovery of its legal costs. Don’t be shocked if others follow.
Litigation Funders: A Cautionary Tale
Funders are highly sophisticated enterprises that understand risk. Before committing capital, they conduct extensive due diligence into everything: merits, quantum, recoverability, timelines.
In backing this litigation, they would have weighed the uncertainties and risks—which in this case were always significant—against the possibility of a payday commensurate with 1.6 million claims.
The judgment mentions that funders were embedded in proceedings and permitted to sit (virtually) alongside claimant firms and insurers, as interested parties.
Now they face some new arithmetic: a narrowed pool of viable claims, an unresolved quantum methodology and the near certainty of an appeal further delaying any return. The scale of return once modeled against a mass cohort has now gone. What remains is a small subset of vehicles and a damages theory yet to be tested.
Closing Thought
Like the tailpipe emissions at the heart of this case, the promised payday has, for most participants, turned out to be mostly vapor, now dispersing into thin, clean air.
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