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Environmental Group Accuses Mercedes of Using Defeat Devices on Diesel Vehicles

German environmental group Deutsche Umwelthilfe (DUH) has published a report that claims that the Daimler Group employs a defeat device in its diesel engines. Their claims are backed by an analysis of a vehicle made by expert Felix Domke. We have the full report.
2013-2016 Mercedes-Benz E-Class T-Modell W212/S212 76 photos
Photo: Mercedes-Benz
Specifications of the tested vehicle2013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S2122013-2016 Mercedes-Benz E-Class T-Modell W212/S212
Before scrolling and rushing to read the 32-page report, let us fill you in on what you need to know. Felix Domke has tested an MY2015 Mercedes-Benz E350d T, which is an Estate version (T-Modell, as Mercedes calls it) of the E-Class W212 generation.

That model had 95.708 kilometers (ca. 59,470 miles) on the clock and was fitted with a six-cylinder engine of the OM 642 type. The 2.987 cubic-centimeter (ca. 182 cu-i) V6 unit provided 254 horsepower (190 kW) and was rated to be a Euro 6 power plant. It is worth mentioning that it has since been replaced by an inline-six-cylinder unit.

Mind you, the entire accusation relies on a single-vehicle being examined. The organization motivates the relevance of its analysis through the fact that vehicle manufacturers can also use the same registration data for a particular engine across several different models. The same type of engine could be found in the GLC, GL, G Class, other versions of the E-Class, and other Mercedes-Benz models of the time.

We must point out that the WLTP norm involves a homologation procedure for each engine and transmission combo, so the part referenced by the DUH may no longer be correct.

According to the expert analysis, the vehicle exceeded its rated emissions in the real world by a factor of 10x when compared to its rated results in the laboratory. In total, Felix Domke found several "defeat devices," as he described them.

These “defeat devices” turn off or reduce the power of some emissions control devices in certain moments, such as limiting the amount of AdBlue used. One of those devices appeared to be activated when the vehicle was operating in Sport mode, when it reduced the amount of AdBlue fluid, according to Jürgen Resch, the federal managing director of DUH.

Other “defeat devices” relied their operation on an "aging factor," which lowered the point where these devices would be turned off or calculated the age of the vehicle and gradually reduced the effectiveness of its emissions control devices, DUH claimed.

Previous accusations against Mercedes-Benz targeted its four-cylinder diesel engines with an SCR filter and AdBlue. At the time, Daimler officials explained that those systems were there to protect the longevity of the engine and its emissions control systems. Various critics of car manufacturers claim that companies rely on too many loopholes and exceptions when their emissions control systems can be turned off.

Meanwhile, regarding these accusations, Daimler officials stated that the "parametrization described were already known," and, from their point of view, “in the interplay and overall context of the highly complex emissions control system, these are not to be assessed as impermissible shutdown devices."
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 Download: Mercedes E350T Emission system analysis (PDF)

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About the author: Sebastian Toma
Sebastian Toma profile photo

Sebastian's love for cars began at a young age. Little did he know that a career would emerge from this passion (and that it would not, sadly, involve being a professional racecar driver). In over fourteen years, he got behind the wheel of several hundred vehicles and in the offices of the most important car publications in his homeland.
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