A landmark legal battle has begun in the UK as hundreds of thousands of motorists seek to prove that Volkswagen was not the only car manufacturer to manipulate emissions during testing. The collective lawsuit, one of the largest of its kind in British legal history, targets several global brands accused of using hidden software to make diesel vehicles appear cleaner than they were in real-world driving. The case builds on the legacy of the 2015 Volkswagen scandal, which exposed the use of so-called “defeat devices” designed to lower nitrogen oxide emissions only during lab testing. While Volkswagen reached a major settlement with UK claimants in 2022, this latest action expands the allegations to include other well-known automakers such as Mercedes-Benz, Ford, Peugeot-Citroën, Renault, and Nissan. The proceedings will determine whether similar systems were used across the industry and, if proven, whether motorists are entitled to compensation. For consumers, the case touches on both financial and ethical issues — from the potential loss in vehicle value to broader concerns about air pollution and public health. Environmental groups argue that excessive nitrogen oxide emissions from diesel engines have contributed to serious health risks across Europe, while automakers insist they followed the rules in place at the time and that their vehicles were fully approved by regulators. Industry representatives maintain that the software under scrutiny was designed to protect engines under specific conditions, not to cheat emissions tests. They argue that the rules then in force allowed for certain temperature or load-based adjustments. However, claimants say this explanation does not excuse misleading consumers or undermining environmental standards. The High Court’s decision is expected to set an important precedent for how emissions cases are handled in Europe. If the court rules in favour of the claimants, the outcome could open the door to billions of pounds in compensation and force manufacturers to confront questions about how they managed compliance with environmental regulations over the past decade. If the carmakers prevail, it would affirm their stance that they operated within a legal grey area created by inconsistent European testing standards. The case also highlights wider tensions between environmental accountability and industrial power. While the U.S. swiftly imposed heavy fines and vehicle recalls following its own diesel investigations, European regulators have taken a slower, more fragmented approach. Critics say this has allowed carmakers to delay technical changes, while defenders argue that Europe’s approval system was complex and slow to adapt to new realities of emissions science. Whatever the verdict, the trial marks a pivotal moment in the post–Dieselgate landscape. Nearly ten years after the scandal first erupted, the issue continues to test not only the integrity of global carmakers but also the credibility of regulators and the resilience of consumer protection laws. CIJ EUROPE View: The UK case underscores a long-running tension between technological innovation, environmental responsibility, and corporate accountability. It is not only a test of who bears blame for the diesel crisis but also a measure of how far Europe has come in aligning its legal systems with its environmental promises.