Diesel Emissions

Tests Reveal BMW, Mercedes Pollution

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A German investigative television report, Frontal 21, said diesel vehicles made by BMW and Mercedes Benz emitted much higher levels of nitric oxide than allowed during road tests in Switzerland. The automakers said their cars met Europe's testing requirements, which only test vehicles for emissions in a lab.
  • Why it matters

    Why it matters

    A German TV news report said it tested diesel cars made by VW, BMW and Mercedes Benz for nitric oxide emissions. All three emitted way more pollutants than in the lab — the only test required by European regulators.

  • Facts


    • The test commissioned by German television network ZDF for Frontal 21 was performed according to official driving guidelines.
    • The three vehicles tested were all models that satisfy Europe’s Euro 5 standard — which is measured only in a lab.
    • The lab tests used in Europe test vehicles at a speed of 21 miles per hour — the driving habits of a senior citizen.
  • Audio


  • Pdf

Volkswagen’s Dieselgate scandal, which involves about 11 million rigged diesel engines of the VW, Audi, Porsche and Skoda brands, is far from over as revelations emerged on rival carmakers BMW and Mercedes and supplier Bosch.

Two diesel cars of rival carmakers BMW and Mercedes and one from VW showed higher emissions values than officially allowed, a German television program reported Tuesday.

In addition, German prosecutors are investigating whether employees of car parts maker Bosch, which supplied VW with crucial parts for VW’s manipulated engines, helped VW to rig software to cheat on emissions tests. VW, already the focus of investigations in the United States and Germany, is also subject to an anti-fraud investigation by the European Union, a German paper reported on Wednesday.

Volkswagen, Germany and Europe’s largest automaker, is embroiled in a global scandal stemming from its rigging of diesel emissions in up to 11 million VW cars around the world to meet environmental standards. After U.S. authorities accused the carmaker of falsified emission values in September, VW admitted it had installed illegal software in diesel cars, which lowered emissions during tests but emitted up to 35 times California’s legal limit of nitrogen oxides when on the road.

A test by investigative program Frontal 21 broadcast Tuesday on German network ZDF compared exhaust values for a laboratory roller test bench with those taken in real driving conditions for a Mercedes-Benz C200 CDI, a VW Passat and a BMW 320d Touring. The results  differed widely, the report asserted, with the road values far exceeding those in the lab, according to the results of tests it commissioned with the University of Applied Science in Bern, Switzerland, which has its own exhaust gas testing facility.


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The tests showed that emissions of nitrogen oxide, a pollutant that plays a crucial role in creating smog, were higher on the road than in the laboratory, the news program said. All of the cars tested were equipped with diesel engines.

It wasn’t a typical drive for Philippe Wili, who first guided the Mercedes across a fenced-off airport and then along the autobahn for a few kilometers. The test driver needed a special permit from the authorities to make his test drive. He was driving unconventionally, to put it mildly, meticulously sticking to the standards of the so-called New European Driving Cycle, or NEDC for short.

The guidelines have been the benchmark for registering new automobiles in Europe for years.

To achieve optimal comparability, test drivers such as Mr. Wili must precisely observe speed limits, acceleration values and a specific number and duration of stops. The tests are also done on specially certified test courses.

The Bern University of Applied Science has one of these courses. Mr. Wili is a test driver there.

As he drove the Mercedes across the open course, Mr. Wili stopped and accelerated according to preset specifications spelled out in the NEDC, which is not the typical driving profile of most Europeans. Experts have compared the NEDC to the driving habits of an older person or, more specifically, an old man. The average speed in the test is 34 kilometers per hour or just 21 miles per hour.

There was a reason Mr. Wili was driving so slowly around the sleepy streets of the Swiss capital.


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The Frontal 21 investigative report highlighted the unrealistic nature of Europe’s current emissions testing, showing how diesel cars made by VW, BMW and Mercedes Benz all failed test limits in real-driving conditions — which are not part of the current testing regimen. Source: DPA / Thomas Eisenhuth


He was performing a drive on behalf of ZDF television network “Frontal 21.” His mission was to compare the exhaust values in the lab, on a roller test bench, and on the road. All three cars tested — the Mercedes-Benz C200 CDI, a VW Passat and a BMW 320d Touring — officially meet Europe’s Euro 5 environmental standard – in the lab, that is.

But according to the broadcaster’s own test, it was a different story when the vehicles were taken on the road.

The diesel vehicles met the exhaust standards in the lab for nitric oxide but the values were several times higher in road traffic, according to the investigative report.

This is not surprising for the VW Passat, one of the models in which exhaust values were falsified using software in an engine control unit, now the focuse of a worldwide probe into Volkswagen’s emissions rigging.

For years, VW manipulated engines with the software to appear to comply with exhaust standards in emissions testing facilities, a problem that VW later admitted affects up to 11 million vehicles made by VW, and its units Skoda, SEAT, Audi and Porsche.

Daimler and BMW had both claimed their vehicles were unaffected by rigging after the VW scandal broke in September. When contacted to respond to the ZDF report, both German automakers did not address the program’s main assertion — that two of their own vehicles, like Volkswagen, appeared to pollute much more on the road than they did in the lab.

“No illegal devices are installed in our automobiles,” BMW said in response to the report. “We want to make it perfectly clear that we refute any speculation to the contrary.”


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Daimler, in a statement, said “vehicles by Mercedes-Benz are in compliance with the regulations in place at the time of registration.”

The luxury automaker based in Stuttgart said it did not use any software to falsify emissions values. “Mercedes-Benz vehicles have no function that automatically detects that the vehicle is in a testing facility,” the automaker said.

Volkswagen boasted of its superior diesel technology, until the automaker in September admitted under pressure from U.S. environmental regulators that it had been cheating. Senior executives in the automaker, which is based in Wolfsburg in northern Germany, have disavowed knowledge of the fraud, and several mid- or low-level employees have been suspended, the carmaker has said.

Beyond questions of executive complicity at Volkswagen, the so-called dieselgate scandal is prodding European lawmakers to tighten testing requirements in all new vehicles to enforce pollution limits under real-driving conditions.

German testing organizations such as Tüv and Dekra, which are close to the country’s automakers, also say they now want to tighten the reins. In the future, the organizations say they plan to measure exhaust data themselves for the first time when new automobiles are registered, rather than relying on industry data as has been the practice, said Axel Stepken, the head of the Tüv-Süd unit for southern Germany.

But the European NEDC guidelines they will enforce are still woefully out of touch with reality, set up by automakers to ensure a lax standard. Daimler and BMW also took issue with the television program’s testing methods.


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One of the three cars tested in the lab and on the road by Frontal 21, a German investigative television program that airs on the ZDF network. Source: BMW


For instance, the outside temperature conducted on the day of the test drive in Switzerland was 10 degrees Celsius (50 degrees Fahrenheit), below the required temperature of 25 degrees. A so-called portable emissions measurement system device was also used during the road test. The device adds to the vehicle weight – and testing personnel usually adjust the results by 24 percent to reflect the difference, which the TV program apparently didn’t do.

The carmakers were also critical of the test cycle, because it cannot be fully reproduced on the road, with its required accelerations and stops. The engineers hired by the TV program in Bern disagree.

The software used in the test provided the driver in the “Frontal 21” report with precise instructions on when to accelerate and brake. Besides, there were differences between the lab and road tests that were difficult to explain.

According to the Bern University of Applied Science report, the emissions value measured with the BMW 320d Touring was 154 milligrams per kilometers, which was below the legal threshold of 180 mg. In the road test, the emissions value jumped to 563 mg per kilometer. In the case of the Mercedes diesel car, the NOx value jumped from 154 to 553 mg per kilometer.

Technical details influence but do not change the overall picture. Through the use of the portable emissions testing device, the results of the road test were about 25 percent higher than in the test laboratory.


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The temperature was also not identical on the two test drives. Neither circumstance changes the fact that the results on the road were much higher than in the lab – and also much higher than the emissions levels known to consumers as the official limit values.

The companies complied with the law, because a car’s registration is based on tests performed on the roller test bench, that is, in the lab, under conditions that do not resemble most driving habits.

The only problem is that pedestrians aren’t inhaling exhaust gases in the laboratory but on the street.

The fact of the matter is that “variances from the normal state required in the laboratory can occur in road tests, due changes in the underlying conditions,” said a Mercedes spokesman. BMW offered a similar response: “The important thing is that the emissions control systems in our vehicles do not distinguish between whether the vehicle is on a roller test bench or on the road.”

Beyond the legalities of the emissions and the culpability of the automakers, the ZDF report seemed to make one thing clear: Europe’s official emissions testing procedures have no teeth, and until they are fixed and made more stringent, consumers on the Continent will continue to be breathing much more pollutants than official limits supposedly allow.


Sönke Iwersen is head of Handelsblatt’s investigative reporting team. Martin Murphy and Markus Fasse cover the auto industry for Handelsblatt. To reach the author: iwersen@handelsblatt.com, murphy@handelsblatt.com and fasse@handelsblatt.com

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