EPA Asks Mercedes-Benz To Provide Diesel Emissions Data, But Stops Short of Official Investigation For Now

Back in September last year, the U.S. Environmental Protection Agency filed the first of several official Notices of Violation against German automaker Volkswagen AG. The notices related to deliberately fitting a so-called ’emissions cheat device’ to certain model-year, 2.0-litre diesel engined, vehicles. Essentially a piece of computer code, the cheat device was designed to ensure that cars met emissions targets when tested on a rolling road (dynamometer) but, in order to give better performance and fuel economy, emitted up to 40 times the legal limit when driven normally.

The EPA has asked Daimler to provide emissions details on all of its U.S. diesel cars.

The EPA has asked Daimler to provide emissions details on all of its U.S. diesel cars.

Since then, more Volkswagen models have been implicated in the scandal, including diesel-powered SUVs sold under the Volkswagen, Audi and Porsche brands. These vehicles were fitted with Volkswagen’s 3.0-litre V6-TDI engine. As multiple investigations around the world have sought to investigate Volkswagen’s illegal actions, so too have other automakers come under scrutiny for their own so-called “clean diesel” vehicles.

One of them is German luxury automaker Mercedes-Benz which, as German newspaper Handelsblatt  (via Reuters) reported this morning, has been asked by the EPA to provide information to explain what appears to be unusually high emission levels in some of its cars. While the EPA is not believed to be undertaking a full investigation at this time, it was prompted to ask Mercedes-Benz’s parent company Daimler for emissions data after a class action lawsuit was filed against the automaker in New Jersey earlier this month.

A variety of diesel-engined cars are claimed to be effected.

A variety of diesel-engined cars are claimed to be affected.

That class action lawsuit, filed by law firm Hagens Berman on February 18, 2016, alleges that certain model-year Mercedes-Benz sedans and SUVs fitted with a range of Mercedes-Benz BlueTEC diesel engines exceed allowable (NOx) levels as set by the EPA in the Clean Air Act, just as many of Volkswagen’s diesel engines did. Citing independent third-party tests carried out by dutch research institute TNO on behalf of the Danish Government, the class action alleges that under average conditions BlueTEC diesel engined cars emit 7.5 times the legal NOx emissions as outlined in the Euro 6 standard for diesel vehicles and 19 time more than the NOx limit set by the EPA.  It notes that instantaneous values during testing rose well beyond that, to 65 times the legal U.S. limit and 25 times more than the Euro 6 limit.

Acting on behalf of a total of 100 plaintiffs, the class action states that one of the causes of such high emissions is the fact that the NOx reduction system fitted to affected vehicles is programmed to operate only when the ambient temperature is above 50 degrees Fahrenheit (10 degrees Celsius).

“Mercedes has admitted that a shut-off device in the engine management of certain BlueTEC diesel cars stops NOx cleaning under these and other, unspecified circumstances,” the court papers detail. This allegation is in turn based on a February 2016 issue of Der Spiegel in which Mercedes is cited as having admitted that the emissions control shut off occurs at lower temperatures to protect the engine.

It’s not clear if this is by design however, or if the exhaust system contains a faulty component similar to the one which caused Renault to recall many of its diesel-powered vehicles earlier this year.

Regardless, the plaintiffs in the case point out that emissions tests for vehicles are carried out at ambient temperatures above the temperature at which Mercedes-Benz’s emissions control system shuts off, meaning vehicles pass EPA standards when tested on the dynamometer. But in a usual winter, the average temperature in more than half of U.S. states dips below that figure. Some struggle to even reach that temperature, meaning that the emissions control system rarely even turns on.

Officially, the EPA is not commenting on the legal case in New Jersey

Officially, the EPA is not commenting on the legal case in New Jersey

Transport Evolved understands that in the light of this legal case, the EPA has asked Mercedes-Benz to provide official test data for its vehicles for verification purposes, although it is not clear at this point what the EPA will do if further inconsistencies are discovered with the data.

In response to our questions, an EPA spokeswoman told us that “The agency does not comment on private lawsuits.” Talking to German newspaper Handelsblatt  — the first publication to cover the story — Christopher Grundler, director of the EPA’s Office of Transportation and Air Quality, confirmed that “We know about the lawsuit. We have contacted Mercedes and requested the test results for U.S. diesel engines.”

During our conversation with our EPA contact, the agency confirmed Mr. Grundler’s statement in Handelsblatt was correct.

As with the rest of the dieselgate scandal, we’ll be sure to update you on this developing story as and when more information becomes available.


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  • Chris O

    There is little doubt VW is just the tip of the iceberg. The fact that everybody in the industry must have known for years about VWs cheating as the industry keeps a sharp eye on each other’s products, yet nobody talked speaks volumes.

    • apm-designs

      Spot on Chris,

      You know in the US at least it would appear there is far more control than in Europe. Here it is becoming a joke and you start to wonder why authorities are not stepping in and preventing all these cheats that are going on and push for a test that does the test on the actual roads that minimize the possibility of any car maker from doctoring the test cycle.
      Here you would have to take of about 50% from the claimed mpg to get the actual mpg of your vehicle and that figure keeps climbing because the test is so outdated and does not conform to modern vehicles that have newer technologies such as start / stop etc….Luckily a new test cycle is coming out called the WLTP, but it is only a matter of time before that starts to get outdated and produce further false results.
      So what you are saying is especially true this end of the pond. Everyone is talking about the environment and yet the authorities allow car makers to make us believe our vehicle is reducing this amount of CO2 & NOx when in fact it is not……disgrace.