“There would be differences between a certification test and a real world test”, said West Virginia University research professor Arvind Thiruvengadam, who was involved in uncovering the emissions test cheating of Volkswagen.


Road tests have revealed that diesel auto models from four major manufacturers have been emitting more pollution that previously thought, according to a report released Friday by the Guardian. His company has been doing more real-world testing of these cars.

The emission testing policies have faced a lot of criticism ever since Volkswagen admitted that 11 million of its vehicles had software created to skirt around emissions tests.

Certain vehicles from Honda, for example, were tested on the road by Emissions Analytics and found to have had over 20 times the NOx limit than in previous tests.

“The VW issue in the USA was purely the trigger which threw light on a slightly different problem in the European Union – widespread legal over-emissions”, said Emissions Analytics CEO Nick Molden. However, it must be mentioned that there is no clear evidence that a cheating device has been used in any vehicle outside of the Volkswagen family. Diesel cars of Mercedes-Benz were producing 0.406g/km of NOx, which is five times higher than the Euro 6 level. Mazda, on average, produced over 1.6 times the legal level.

A Honda spokesperson told the Guardian that the company tests cars in accordance with European legislation, and a Mazda spokesperson said Mazda tries to make sure all its vehicles comply with emissions regulations.

Last week the Guardian published data indicating that cars from Renault, Nissan, Hyundai, Citroen, Fiat, Volvo and Jeep could be dirtier than advertised. The company was quick to issue a statement, saying that “Real-world driving conditions do not generally reflect those in the laboratory, and so the consumption figures may differ from the standardized figures”.

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