In addition to Volkswagen and Audi, diesels by five other carmakers have been found to produce more NOx in the real world than in laboratory settings.

The assessment, as reported by The Guardian, was performed by the U.K.-based Emissions Analytics. Using Euro 5 and Euro 6 European emission standards, the firm showed that only than 2.5 percent of diesels they tested deliver identical real-world and laboratory results. Honda, Mazda, Mercedes-Benz, Mitsubishi, Fiat, Nissan and Volvo were among the manufacturers named.

“The issue is a systemic one” across the industry, said Nick Molden, founder and CEO of Emissions Analytics. “The VW issue in the U.S. was purely the trigger which threw light on a slightly different problem in the EU – widespread legal over-emissions. For NOx, [diesel] cars are on average four times over the legal limit, because of the lenient nature of the test cycle in the EU.”

Specifically, The Guardian reported the following results from Emissions Analytics:

  • “Mercedes-Benz’s diesel cars produced an average of 0.406 grams/kilometer of NOx on the road, at least 2.2 times more than the official Euro 5 level and five times higher than the Euro 6 level.”
  • “Honda’s diesel cars emitted 0.484 g/km of NOx on average, between 2.6 and six times the official levels.”
  • “Mazda’s diesel cars had average NOx emissions of 0.293 g/km in the real world, between 1.6 and 3.6 times the NEDC test levels. One Euro 6 model, the Mazda 6 2.2L 5DR, produced three times the official NOx emissions.”
  • “Mitsubishi diesel cars produced an average of 0.274g/km of NOx, between 1.5 and 3.4 higher than in the lab.”

In separate statements, representatives from Honda and Mazda noted that their vehicles are in compliance with European regulations. Other companies acknowledge that testing done in a lab doesn’t accurately replicate real-life settings.

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“Since real-world driving conditions do not generally reflect those in the laboratory, the consumption figures may differ from the standardized figures,” explained a spokesperson for Mercedes.

“The [New European Driving Cycle] was never intended to represent real-world driving,” a Mitsubishi representative told The Guardian.

This issue with carmakers such as Honda and Mazda is not that the tests were cheated, but the testing methods need an overhaul. Other than Volkswagen, European officials have not yet detected defeat devices in any other carmaker.

In the U.S., the Environmental Protection Agency announced it will be retesting many diesel cars. Instead of requesting vehicles from the automakers, the EPA will be renting or borrowing vehicles to analyze, compensating the owners for their assistance. The EPA has not yet released any findings on the new tests or said if it suspects other carmakers of using defeat devices.