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Daimler launches diesel plan; expands recall to >3M units, accelerating next-gen diesel launch

The Daimler Board of Management has approved a comprehensive plan for diesel engines consisting of a substantial expansion of the current service action for vehicles in customers’ hands as well as a rapid market launch of the completely new OM 654 diesel engine family (earlier post).

Since March, Mercedes-Benz has offered its customers of compact-class cars an improvement in NOx emissions for one engine version. Approximately 45% of those cars have since been updated. A voluntary service action is also being carried out for V-Class customers—so far with approximately 75% of the vehicles in Germany. To improve the emissions of additional model series, Daimler has now decided to extend the service action to include more than three million Mercedes-Benz vehicles.

The public debate about diesel engines is creating uncertainty—especially for our customers. We have therefore decided on additional measures to reassure drivers of diesel cars and to strengthen confidence in diesel technology. We are convinced that diesel engines will continue to be a fixed element of the drive-system mix, not least due to their low CO2 emissions.

—Dr. Dieter Zetsche, Chairman of the Board of Management of Daimler AG and Head of Mercedes-Benz Cars

For this purpose, the company’s engineers are making use of latest knowledge gained during the development of the new OM 654 family of diesel engines.

The measures to be taken for nearly all EU5 and EU6 vehicles in Europe will be carried out in close cooperation with the German regulatory authorities. The company is investing about €220 million (US$254 million). The service actions involve no costs for the customers. The implementation of the measures will be starting in the next weeks. Due to the large number of vehicles this will continue over a longer period of time.

In this way, Daimler says it will makea significant contribution to the reduction of nitrogen-oxide emissions from diesel vehicles in European inner cities.

New engine family. Mercedes-Benz has already proven that diesel engines can meet the stricter EU emission regulations to come in the future with a completely new engine family. With an investment of approximately €3 billion (US$3.5 billion), the company has developed a new generation of engines the exemplary emissions of which have been confirmed by measurements carried out by independent institutes.

Following the market launch of the new four-cylinder OM 654 engine in the new E-Class in 2016, the launch of the modular engine family will now be implemented rapidly across the entire model portfolio.

The new OM 654 for the E-Class delivers around 13% lower fuel consumption and CO2 emissions along with a further increase in output (143 kW instead of 125 kW) compared to its predecessor, the OM 651.

The new diesel engine is designed to meet future emissions legislation (RDE – Real Driving Emissions). In contrast to the current NEDC measurement cycle, the WLTP (Worldwide harmonized Light vehicles Test Procedure) cycle is aimed at ensuring that the figures for standard and real-world consumption are close together in future.

All components of relevance for efficient emissions reduction are installed directly on the engine. With support from insulation and improved catalyst coatings, there is no need for engine temperature management during cold starting or at low load. In addition to the advantages in terms of emissions, this results in fuel savings, especially on short journeys. Due to the near-engine configuration, exhaust aftertreatment has a low heat loss and optimal operating conditions.

The new engine is equipped with multiway exhaust gas recirculation (EGR). This combines cooled high-pressure and low-pressure EGR. It makes it possible to significantly further reduce the untreated emissions from the engine across the entire engine map, with the center of combustion being optimized for fuel economy.

The exhaust gas from the turbocharger is sent first to a diesel oxidation catalyst. It next passes the downdraft mixer, in which AdBlue is added by means of a water-cooled dosing module. Using a specially developed mixing area, the AdBlue evaporates over the shortest possible distance in the exhaust gas stream and is distributed very uniformly on the surface of the downstream sDPF (particulate filter with coating to reduce nitrogen oxides). Positioned behind the sDPF is an SCR catalyst for further catalytic reduction of the nitrogen oxides. Only then does the treated exhaust gas enter the exhaust system.

Daimler will continue to work on the systematic electrification of its vehicles, support mobility services such as moovel and car2go, and develop increasingly clean combustion engines. Daimler says that diesel engines will continue to play an important role for a long time yet due to their significantly higher efficiency than gasoline engines.



So they skimped on the emissions controls for a saving of less than $100 per car?

Tells you all you need to know about Daimler's attitude.

And they continue to talk cobblers about how wonderfully clean diesels will be, which make no mistake about it, the see as the primary dive unit going forward.

Not when any ICE engine and its catalytic converter are cold, they aren't low emission:

'Unfortunately, the majority of vehicles Emissions Analytics has tested take more than 5 minutes to warm up their emission-control systems fully.

It's the same reason that in hybrids and plug-in hybrids, when the engine kicks on for the first time after a period of electric-only operation, it usually stays on for 2 to 5 minutes before switching the car back to the default mode of all-electric power.

While those engines are specially fitted and tuned to warm up exceptionally quickly and remain low-emission in frequent on/off cycles, they still must heat their catalytic converters to temperatures of several hundred degrees F.

Across all the cars Emissions Analytics has tested, it calculated that even after 5 minutes, the average NOx emitted by diesel engines of all ages is 7 times the legal limit for new cars today(0.08 g/km) when fully warmed up and about 30 percent more than that when cold.

Gasoline engines suffer from much higher NOx emissions when cold versus when they're warm.

According to the company's calculations, gasoline engines are 4 times over that limit when cold, but emit less than half the maximum permissible NOx once fully warmed up.'

Juan Valdez

Gassers are rapidly transitioning to hybrids then to full EVs, and diesels are dead, apparently Daimler didn't get that memo.

I can't believe Daimler is investing 3 billion in diesels!! Probably driven by the attorney as a defensive move.

Think about the electrificiation platforms could be designed and launched with 3B. Makes you wonder about Daimlers long term viability.


All laboratory test cycles include a cold start. It has been so since the 1970's. Thus, a cold start is always part of the test results. The relative impact varies between the different test cycles. In fact, the ”old” European NEDC test cycle is actually one of the toughest (that I know of) in this respect. This furthermore aggravated by the “slow” city driving after start. The impact in the US FTP test is roughly less than half of that in NEDC, since the driving distance per cold start is more than twice as long in FTP. The impact of the cold start will be somewhat less in the new WLTP cycle than in the NEDC cycle. WLTP is based on logging of huge fleets of cars around the world and should be representative of normal driving. The cycle is based on the latest and best knowledge we have on how cars are used in real traffic. Still, this is not sufficient to regulate emissions under all driving conditions and this is why the on-road testing is now introduced in the RDE legislation in Europe.

I have not studied how Emission Analytics do but according to the new European RDE testing, a cold start should be included. Unfortunately, there are a number of organizations and companies out there who conduct testing and their results may not always be representative of “real-world” driving. They often highlight some specific driving condition. It is not uncommon that on-road tests are only conducted with warm engines; primary to save time and cost. All-in-all, consumers get misinformed by all the headlines such tests may create.

Note that “cold start” usually is defined as a start with cold engine at ~25°C. Cold starts at lower ambient temperatures increase emissions much more than at 25°C. EU regulates this for CO and HC from gasoline cars at -7°C, albeit that the limits are much higher than in the standard test. Cold start emissions of CO and HC are considered much lower from diesel cars and thus, they do not have to be tested. This is based on comprehensive knowledge on results in cold starts in the past. The main problem for cold starts is unregulated emissions that pose health hazard for humans. Gasoline cars are much more affected than diesel cars in this respect (therefore, we want to regulate HC at cold starts). The difference in relative levels can be in the range of 10-100. NOx is generally not a problem during cold starts, since the engine-out NOx is lower (due to lower NO formation) than in a hot start, unless the manufacturer “cheats” in some way.

Stopping the engine via conventional start/stop systems or in a hybrid drive is not necessarily “bad” for emissions. This is of particular relevance to consider for engines with low exhaust temperature, such as e.g. lean-burn gasoline engines and diesel engines. At idle, the exhaust temperature might be lower than catalyst light-off temperature and leaving the engine on idle will cool down the catalyst. Stopping the engine gives much lower heat loss and thus, higher catalyst efficiency. You have perhaps noted that there have been several articles on mild/micro hybrid diesel cars that reduce NOx emissions compared to conventional diesel cars on this site. Synergies via hybrid systems can be identified not only regarding higher catalyst temperature but this will be another topic.



Thank You - Great Comment. The fact that you are using real information and not emotion is refreshing.


Even thirty years ago, it was common knowledge in the industry that every vehicle "failed the first bag" because the catalyst was cold.

One of the responses I saw was an electrically pre-heated catalyst cartridge, so the catalyst would "light off" right away.  It had a terminal that took a starter-sized power cable.  I can only imagine the size of the battery required to feed that thing.

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