Studies conducted by the DUH, the University of Applied Sciences in Bern, Switzerland, and the UK's Leeds University found that Opel's diesel Zafira, Corsa, and Vectra models emit more NOx than European regulations allow when tested in ways that go beyond the European testing protocol, such as when done on a four-wheel rolling road instead of a two-wheel rolling road. Opel said the accusations had no merit. Specifically on the Zafira, the DUH asked Opel about the emissions findings, and Opel said that no General Motors software contains any measures to enable cheating. Opel then tested a Zafira of its own "both on a two- and a four-wheel roller dynamometer," finding that "The emission behavior determined in each case does not differ from one another." That makes this a case of he-said-she-said for the moment.
The Daily Kanban's sources say the cheating methods "range from the crude to the highly sophisticated," with those at the latter end complex enough to render Volkswagen's methods "pedestrian." As for any automakers who might be named, the matter of real-world emissions exceeding a legal limit doesn't mean a carmaker has designed systems that cheat, it might mean the company designed the car to pass a test.