Diesel engines emitted 14 times limit for parts of ‘real-world trips’, tests in 2011 showed

By Mike Yuille | 9 March 2016

“It was widely known for years that real emissions of cars were nowhere near the set targets” – Rebecca Harms, Green MEP

European Commission technicians discovered in 2011 that in real-world tests diesel cars were emitting up to four times maximum limits of poisonous nitrogen oxides. And, for parts of the test trips, emissions averaged 14 times the legal level.

Their findings are set to be raised in an inquiry by the European Parliament into what went wrong with the regulation of vehicle emissions.

Technicians at the EC’s Joint Research Centre (JRC) used “portable emission measurement systems” (PEMS) in 2011 to test real-road emissions of nitrogen oxides (NOx), carbon dioxide (CO2) and other gases from 12 light-duty diesel and petrol vehicles that officially complied with the latest emissions limits.

As a result, the JRC compiled a damning report that year, saying: “The findings of this report indicate that the current laboratory emissions testing fails to capture the wide range of potential on-road emissions.

“A promising remedy for this problem may be attained by supplementing laboratory emissions testing with complementary test procedures such as PEMS on-road emissions testing.”

The JRC’s specialist researchers tested 12 vehicles, including nine small and mid-size passenger cars, two small transporters, and a minivan. Six vehicles had diesel engines, five had petrol and one was a petrol-electric hybrid. The technicians drove each vehicle on four routes from and back to the JRC in Ispra, north-west Italy. The test routes represented rural, urban, uphill/downhill, and motorway driving.

The diesel vehicles’ emissions of nitrogen oxides “substantially exceed” maximum levels, according to the report.

It said: “The observed deviations range from a factor of two-four for average NOx emissions over entire test routes up to a factor of 14 for average NOx emissions of individual averaging windows.”

The petrol vehicles, by contrast, were within the limit for nitrogen oxides.

Emissions of carbon dioxide were 24 per cent above maximum levels for the diesel vehicles, and 18 per cent beyond the limit for the cars with petrol engines.

The report concluded: “The PEMS results indicate that on-road NOx emissions of light-duty diesel vehicles differ substantially between laboratory [European-standard] testing and actual on-road driving.”

According to the report, the tests “confirm earlier findings” in one scientific paper of 2009 and in another as far back as 2006.

The EC study, and academic papers, will come under scrutiny by a “committee of inquiry” by the European Parliament into the regulation of vehicle emissions. The inquiry is due to begin work later this month.

Rebecca Harms, a German Green MEP and member of the committee of inquiry, told Exaro: “It was widely known for years that real emissions of cars were nowhere near the set targets.”

“Given the severe health impact of emissions of nitrogen oxides,” she continued, “this failure to act will have to be addressed by the inquiry.”

Exaro revealed last month how by the EU failed to tackle car makers over the cheating of emissions tests despite a clear warning in 2012.

The EC says that it needed time for the development of the technology for real-world testing.

Bas Eickhout, a Dutch Green MEP who is also a member of the committee of inquiry, was unconvinced, saying: “In 2007, we asked the Commission to develop new tests. It has taken all this time to reach a deal.”

On the inquiry, he said: “Let us achieve an insight into why Europe failed for so many years in addressing these problems.”

The European Union is only due to introduce new rules this year to impose real-world testing for vehicle emissions, cutting the potential for rigging by car makers.

However, the rules will be accompanied by “conformity factors” to allow more than double the level of emissions of nitrogen oxides than the “maximum” limit.

Under current EU regulations, vehicles can emit up to 80 milligrams per kilometre (mg/km) of nitrogen oxides. When real-world testing is introduced, new cars will be allowed to emit 168mg/km, reducing to 120mg/km in 2020.

Concern about weaknesses in Europe’s regulation of vehicle emissions has grown since America’s Environmental Protection Agency (EPA) revealed in September that Volkswagen was cheating tests for nitrogen oxides by using “defeat devices”, or specialist software, in diesel engines.

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