Some Japanese car diesel emissions are higher on the road than in laboratory tests

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TOKYO – Japanese officials said they found on-road emissions to be much higher than in laboratory tests of certain diesel-powered vehicles manufactured by Toyota Motor Corp., Nissan Motor Co. and Mitsubishi Motors Corp. sold in Japan.

Two Toyota vehicles and one Nissan vehicle tested on the road emitted up to 10 times the amount of nitrogen oxides, or NOx, than the standard they had to meet in laboratory tests, while a Mitsubishi vehicle emitted up to five times the amount of NOx it needed to meet in a lab test, Japan‘s Transportation Ministry said in documents released earlier this week.

The Japanese Ministry of Transport tested six types of diesel vehicles. No illegal software was found in the cars tested and the automakers did not violate any regulations, officials said. Diesel vehicles sold in Japan are currently only subject to lab tests for emissions, but the government is considering adding road tests. Regulators in Europe and the United States are also discussing similar measures.

The Japanese testing was part of a global reaction to the Volkswagen AG emissions scandal, in which the German automaker last year admitted to using illegal software to manipulate the test results of certain diesel cars.

The results are the latest example of the discrepancies between emissions from lab tests and those from field tests, which industry experts have warned against for years.

France, which set up a special commission last year to oversee testing of 100 cars under real conditions, said in January that several cars tested by the commission, including a Renault SA model, were found with excessively high exhaust emissions.

In Japan, the vehicles with the biggest emissions differences were certain versions of Toyota’s Hiace van and Land Cruiser Prado sport utility vehicle, Nissan’s X-Trail SUV and Mitsubishi’s Delica D: 5, all sold in Japan. , the ministry said.

In contrast, the CX-5 from Mazda Motor Corp. in road testing gave almost the same emissions result as the lab test standard, while the Demio, known as the Mazda2 overseas, had only a small gap between the standard laboratory and field. test result, authorities said.

The X-Trail and Delica D: 5 emitted more NOx than standard in initial lab tests, then hit the standard in subsequent tests, the ministry said. This is not a problem, an official said, because before cars are approved for sale, several vehicles are tested and the average emission figure of those vehicles is compared to the norm. In these latter tests to assess the emissions deviations, only one vehicle of each version was tested and, therefore, an average could not be calculated.

Toyota “will continue to make improvements to reduce NOx emissions when using on-road vehicles,” a company spokesperson said. “Nissan will continue to develop and launch highly efficient, low-emission powertrains,” a spokesperson said. Mitsubishi “will continue to obey the law and regulations around the world and strive to develop new emission reduction technology,” a spokesperson said.

The Japanese market for diesel cars is small. Last year, diesel-powered cars accounted for around 4% of total passenger car sales, including minivans with 660cc engines.

In Japan, diesel vehicles must pass a 20-minute lab emissions test before being approved for sale. The test involves a cycle of acceleration and deceleration, with a top speed of approximately 82 kilometers (51 miles) per hour.

To determine whether automakers were using illegal software, the ministry said it carried out laboratory and field tests, driving cars on a set route that included urban roads and highways to assess NOx and carbon emissions. others.

The emissions deviations most likely appeared in Toyota and Nissan vehicles, because when the cars were tested on the streets, the cold prompted the vehicles to activate a feature that protects the engine from damage, the ministry said. This has led the vehicles to deactivate a system called exhaust gas recirculation which reduces the formation of NOx, for a set period of time, he said.

Toyota said it also sells Hiace diesel pickup trucks in Hong Kong, Singapore, Chile and Russia. Nissan said different versions of the diesel X-Trail are sold primarily in Europe, while Mitsubishi said the Delica is an exclusively Japanese model.

Write to Yoko Kubota at [email protected]

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