Improving the Diesel is better than banning it.

Why we still need a mix of drive technologies in the future, the role the modern diesel engine has to play and why we rely on innovation instead of bans.

After the judgment issued by individual courts in recent weeks, it seemed the death knell had been sounded for the diesel engine as a drive variant: an allegedly outmoded technology and the main cause of excessive levels of pollution in cities and metro areas. This, at least, must be the impression of many consumers if they gave credence to the headlines and commentary in the media in recent weeks.

First and foremost: As an automotive manufacturer we are not seeking to dodge the issues or make things seem better than they are. We are clear that we bear responsibility for reconciling the demands for individual mobility, climate protection and clean air.

And that is precisely why we fully back the diesel engines of today as a part of the drive mix of tomorrow:

• First, diesel engines still enjoy an undisputed advantage in respect to CO2 over comparable gas engines. Not using this technology on the road toward electric mobility would therefore be counterproductive, at least in terms of climate policy.

• Second, as a result of our experience over the last few years we can improve the NOx emissions of many vehicles on the road -- both effectively and relatively swiftly -- through software updates.

• And, third, since the changeover to WLTP and RDE, the market penetration of vehicles with the new generation of engines, as well as vehicles with Euro 6d-TEMP certification, has really been picking up speed. These record emissions that are in many cases under - and in some cases significantly under - the laboratory threshold value of 80 mg/km in normal driving operation.

To put it succinctly: To do away with the diesel at this point in time would be a big mistake, for both environmental and economic reasons.

The recent court judgments about possible driving bans in certain cities do not change this situation in the slightest.

As a company that, for more than 130 years now, has demonstrated its total commitment to helping people be mobile we reject driving bans, which are a forced restriction on mobility.

We are convinced that it is possible to bring the violation of threshold limits under control in cities, too – without driving bans and with the diesel. The objective reasons and technical facts supporting our position are provided below:

1. NOx emissions are continuously decreasing thanks to new engine technologies

The differences between laboratory and road-test measurements of the pollutants emitted from diesel vehicles have, understandably, led to many questions. In the current debate, however, the impression is often given that nitrogen oxide (NOx) pollution in Germany has never been so high. But, in fact, the opposite is true. According to the German Federal Environmental Agency, the pollution caused by traffic has fallen by around 70 percent since 1990. And this despite traffic volumes rising significantly in the same period.

It's clear that the NOx threshold limits at measuring stations close to traffic are still exceeded. But it is also a fact that, since 2016 there were already no violations of threshold limits at the monitoring stations in urban areas more removed from heavy traffic.

A study published in 2016 that was backed by the Federal Ministry for the Environment, Nature Conservation and Nuclear Safety, the German Environment Agency, and the German Association of the Automotive Industry among others, predicted that by 2020 the expected renewal of vehicle fleets would reduce by about 50 percent (compared to 2015) the number of monitoring stations located near road traffic that record NO2 emissions exceeding the limit values. Five years later, a reduction of more than 80 percent would be possible. In other words, the study already showed in 2016 that the fleet update alone is a very effective means of improving air quality. However, the study also came to the conclusion that this will not be enough to ensure compliance with the limit values in the medium term in locations with high exceedances such as those in Stuttgart and Munich. It must be added here that back in 2016 the researchers could not yet take into account the many additional measures that have been initiated since then in order to reduce NOx emissions and improve air quality. These measures are described further below.

In the current debate, particulate matter and NOx are mixed up time and again. The problem of particulate emissions caused by diesel engines could be solved with the introduction of diesel particulate filters.

Mercedes-Benz already equipped a diesel car with a filter back in 1985. The lessons learned from this program formed the basis for the development of innovative and highly effective filter technologies. Filters have been standard equipment for Mercedes diesel vehicles since 2005. Of course, there are still older vehicles on the road. Nevertheless, total particulate matter emissions from engines are low by comparison with other sources. According to the German Federal Environmental Agency, engines are only responsible for 7 percent of particulate matter emissions on the Neckartor road in Stuttgart.
Expert opinion written by Dekra lists other sources of particulate matter emissions, using Stuttgart as an example.
The total volume of particulate matter emissions in Germany has continued to decrease in recent years. The sources of particulate matter are diverse. Gasoline engines and — since the introduction of diesel particulate filters — diesel engines as well are responsible for only a small proportion of total particulate matter emissions. For example, less than 10 percent of the particulate matter emissions (PM 10) on the well-traveled Neckartor road in Stuttgart come from gasoline or diesel engines.

The fine PM 2.5 emissions have been subject to an annual average target value in Europe of 25 µg/m3 in the outside air since 2010. This value has been binding since 2015. The most recent breach of this value was recorded by the German Environment Agency in 2010. No exceedances of this limit value have been registered in Germany since then.
For the coarser PM 10 emissions, an annual average value of 40 µg/m3 has applied since 2005. The most recent measurement to exceed this value was recorded in 2011. For PM 10 there is also a daily limit value of 50 µg/m3, which may not be exceeded more than 35 times within a year. Since 2016, this value has been exceeded only on the Neckartor road in Stuttgart.
The number of days on which the limit value of particulates has been exceeded in 2018 makes us optimistic that the standard can be complied with this year. This would mean that in 2018 no German city has exceeded the limit for particulate emissions.

We believe that the positive trend in the figures for NOx emissions in particular will intensify further in the near future. Three developments in particular will play a critical role in this: First, vehicles with the latest-generation diesel engines are coming to the market in ever greater numbers. Second, more and more vehicles are being offered that are certified to the latest and therefore most stringent emissions standard to date - namely the Euro 6d-TEMP. And, third, the measures adopted at the "diesel summit" are having an effect.

a. The latest generation of engines

Since 2016, Mercedes-Benz has been offeringalready had the crucial innovations in the further development of diesel technology in its series-produced cars for two years now. The four-cylinder diesel engine OM 654 with a combination of exhaust-gas aftertreatment close to the engine, stepped combustion bowls and further developed multiple exhaust gas recirculation was already introduced in the Mercedes-Benz E-Class in April 2016. Since then, Mercedes-Benz has systematically adapted its product portfolio to the new generation of diesel engines. For that purpose, the company has invested approximately three billion euros in research and production.
Following the launch of the new generation of diesel engines in the E-Class (four-cylinder OM 654) and the S-Class (six-cylinder OM 656), the four-cylinder OM 608 is being introduced in May 2018 in the new A-Class A 180 d (fuel consumption combined: 4,5-4,1 l/100 km combined CO2 emissions: 118-108 g/km). The new diesel engines from Mercedes-Benz are therefore now available from the compact class to the large, luxury class.

Vehicles fitted with these engines have low NOx emissions also on the road: Indeed, on many trips using the Real Driving Emissions (RDE) measuring process, they record values significantly lower than the current laboratory threshold limit of 80 milligrams. For example, in a test conducted by the magazine Auto Motor und Sport (issue 18/2017) the Mercedes E 220 d (fuel consumption combined: 4.4-3.9 l/100 km; CO2 emissions (combined): 112-102 g/km)¹ recorded 41 milligrams of nitrogen oxide per kilometer. Other organizations, such as technical services providers and automotive newspapers have confirmed very good values in road tests.

Current Mercedes-Benz vehicles equipped with the latest diesel technology can achieve NOx emissions in a very low double-digit and sometimes even single-digit range in some RDE-measurements on the road. For instance, one technical services provider tested a wagon version of the new C-Class with a new 1.6-liter four-cylinder OM 654 engine according to the currently applicable RDE regulations, and measured nitrogen-oxide emissions below 10 milligrams per kilometer in the overall cycle, both with and without cold starts. When a sedan version of the new C-Class with the same engine was tested in accordance with the RDE method, NOx emissions of approximately 10 milligrams per kilometer were measured.

However, average emissions over many thousands of kilometers as described above are much more meaningful than individual measurements. We also achieve average emission results of about 40 to 60 milligrams in our internal test measurements for continuous operation, covering many thousands of kilometers in both urban and long-distance driving.

At low levels of engine load, for example while driving slowly, the effectiveness of exhaust-gas aftertreatment could be substantially enhanced due to the close proximity of the system to the engine and further developed exhaust-gas temperature management, thus significantly increasing the system’s effectiveness in the city. Also the temperature range at which exhaust treatment works particularly effectively could be extended significantly with the new engines, without any of the components being damaged. Average NOx values that are well below the laboratory value of 80 mg/km are therefore achieved in normal driving operation at low temperatures, too.

The OM 654.

The new engines have yet more potential for future improvement, so we can assume we will be able to reduce NOx emissions further still. Ola Källenius, Member of the Board of Management of Daimler AG, responsible for Group Research and Mercedes-Benz Cars Development: “Our goal is to arrive at average NOx emissions of around 30 milligrams per kilometer in RDE Stage 2 tests by 2020. And we are determined to achieve averages approaching 20 milligrams in the following years. We are targeting these figures in particular for our vehicles on RDE driving tests in cities.”

One of the levers is the continuous improvement of the interaction of the various components in the overall system – which includes the highly complex engine-management system. In addition, new and sophisticated hardware will be introduced in the years ahead — for example, the underfloor SCR catalytic converter that was mentioned above.

Figure 1: German Technical Inspection Authority and DEKRA PEMS measurements at differing temperatures of the OM 656 and OM 654 diesel engines in Mercedes Benz vehicles. The values are also significantly below the laboratory threshold limit of 80 mg/km and the RDE threshold limit for EU6d-Temp (level 1) of 168 mg/km at low temperatures.

b. EURO 6d-TEMP certification

As the study mentioned above shows, the updating of the fleet with new diesel vehicles certified according to the Euro 6d-TEMP or Euro 6 d standards is a very effective measure to further reduce NOx emissions in road traffic. At Mercedes-Benz Cars, the entire fleet for Europe has been certified according to the WLTP standard — in other words, at least according to the Euro 6 c Standard — since the beginning of September 2018. More than 80 percent of the vehicles in our current product portfolio — i.e. over 30 models and more than 200 variants — are already certified according to the Euro 6d-TEMP Standard (RDE Stage 1)².

In other words, we are already offering our customers a broad spectrum of Euro 6d-TEMP vehicles. What’s more, we have already presented the new B-Class with a two-liter diesel engine and the new GLE with a three-liter six-cylinder diesel engine — the first models that already meet the Euro 6d Standard. This has been made possible by the expanded exhaust gas aftertreatment using an additional underfloor SCR catalytic converter. These are thus the first models from Mercedes-Benz that are certified according to the Euro 6d Standard, which will only go into effect on January 1, 2020.

To gain Euro 6d-TEMP or also of course Euro 6 d registration vehicles must also for the first time also pass an RDE test. The threshold limits for Euro 6 d-TEMP are currently 168 mg/km, and for EURO 6 d 120 mg/km. Vehicles must stay within these limits in every imaginable type of RDE trip that complies with the statutory provisions. If the vehicle exceeds the threshold limit just once, certification might not be possible. The vehicles certified according to the new emissions standards have therefore been further developed so that a suitable margin from the 168 or 120 mg/km threshold can be maintained. So, for the vast majority of trips in normal driving operation, emissions are significantly lower than the limit values (see Figure 2). On average, most vehicles record values significantly under the 80 mg/km limit in normal driving. This explains why the rapid penetration of the existing base of vehicles by vehicles with the new certificate will significantly improve air quality in terms of NOx emissions.

Figure 2: Example of the frequency distribution of RDE measurements in two Mercedes-Benz vehicles. To achieve certification, the Euro 6d-TEMP RDE threshold limit of 168 mg/km may not be exceeded. In the vast majority of journeys, however, emissions are significantly lower. This explains why rapid penetration of the existing base of vehicles by vehicles with the new certificate will significantly improve air quality.

Meanwhile, engineers at Mercedes-Benz are also using the lessons learned from field testing and the development of the new family of diesel engines to improve emissions on vehicles that are not yet certified to Euro 6d-TEMP, too. A bundle of measures has been feeding into series production since the end of 2016.

2. The measures adopted at the "diesel summits" are starting to take effect

In addition to the above-mentioned rapid introduction of vehicles that fulfill the more stringent emissions limit values as part of the RDE requirements, we are using a series of further measures to quickly improve air quality — always with the goal that our customers’ mobility should not be limited by driving bans.

The measures at a glance:

1. The rapid introduction of vehicles that meet the stricter emission limits required as part of the RDE testing procedure.

2. Software updates for well over 3 million vehicles in Europe (of these, well over 1 million of them are in Germany)

3. Support for the German federal government’s clean air concept, with attractive exchange premiums of up to €10,000 for diesel vehicles, and participation in a hardware retrofitting program in the defined priority regions.

4. Participation in the German federal government’s mobility fund ("immediate action program for clean air").

5. Many other local and regional measures, especially in the Stuttgart region.

a. Software updates

In order to rapidly improve emissions from EU5 and EU6 vehicles in Europe, we had already decided to extend our ongoing servicing measures to over 3 million vehicles even before the "diesel summit" in August 2017.

After talks at the German Federal Ministry of Transport and Digital Infrastructure (BMVI) in June 2018, Daimler was also ordered by the German Federal Motor Transport Authority (KBA) to conduct a mandatory recall of approximately 690,000 vehicles in Europe (including approximately 280,000 in Germany). The great majority of the vehicles subject to recall were already covered by Daimler’s program of voluntary service measures. Both of these measures include software updates. Through these measures, Daimler will improve the NOx emissions of a large proportion of the Mercedes-Benz Euro 5 and Euro 6 vehicles in Europe by an average of 25 to 30 percent in normal operation.
Across all vehicles, NOx emissions will reduce on average by 25 to 30 percent in normal driving operation as a result. For example, in a test conducted by "Auto Motor und Sport"on a Mercedes-Benz V-Class, NOx emissions were reduced by more than 80 percent following the software update. This reduction is just one example; it will surely not be possible to achieve the same result on average and in all model series. Nevertheless, with software updates NOx emissions can be rapidly and effectively reduced in many model series.

And our experience with the ongoing measures indicates that the updates are being taken up in very large numbers by our customers: As an example, since March 2017 we have been able to implement a software update for about 95 percent (as of May 2018) of our diesel entry-level compact class models (Mercedes-Benz A-Class, B-Class, GLA and CLA) in Germany.

Many may be asking themselves why we are able to improve the emissions of vehicles out in the field now and not before; and why so clearly with the aid of software updates alone.
There is an explanation for this: Our developers are continuously working on making the various components and functions work better together. The same is true for the highly complex engine controls. We have made great progress in this area in recent years: Our engineers have used the lessons learned from the development of our new diesel engine family and experience from the field, as well as from ongoing measures still in progress for updates. This has allowed us to take many vehicles closer to their system limits without significantly increasing the risk to the quality of the vehicles.

b. Our position on hardware retrofit solutions

We are, of course, looking very intensively at hardware solutions. A hardware conversion nearly always means a far-reaching intervention into the control system and vehicle architecture. Hardware retrofit solutions have to be developed individually for each model. In particular, we must also ensure that converted systems are capable of delivering their full functionality and meeting our quality and safety standards over the long term. An article in the Frankfurter Allgemeine Sunday paper describes these challenges.

Our basic assessment of the topic has not changed: We do not believe that a comprehensive retrofitting of existing vehicles with exhaust gas aftertreatment units in Germany and Europe would be practicable.

Nonetheless, we have indicated our willingness to participate in a hardware retrofitting program for diesel vehicles within the framework of the German government’s concept for cleaner air and safeguarding individual mobility. The program is limited to the defined priority regions. Specifically, we will cover the cost of a hardware retrofit up to a maximum value of €3,000 for Mercedes-Benz customers with Euro 5 diesel vehicles. Daimler will not develop or offer a retrofit solution of its own as part of this commitment. This can be carried out by a third-party provider. In addition, the retrofitting must be certified and approved by the German Federal Motor Transport Authority (KBA) and demonstrably authorize entry to certain cities including driving on roads affected by the driving ban.

We are already conferring with retrofitting providers in order to create transparency concerning what hardware solutions are on offer and when they will be available. We are also providing the information that the third-party providers need in order to decide on the model series for which they want to develop and offer hardware solutions.

In the end, one thing is perfectly clear: We still believe that in the priority regions as well, other measures would be more suitable and more efficient overall — in particular, the accelerated renewal of the vehicle fleet and the application of software updates.

c. Exchange Premium

Daimler is also supporting the German federal government’s concept for cleaner air and the safeguarding of individual mobility by means of a premium program. Customers in the priority regions who already own a diesel car conforming to Euro 1 through Euro 4, and now for the first time also Euro 5, and who choose a new Mercedes-Benz gasoline, diesel or hybrid car conforming to the Euro 6 d-TEMP or the Euro 6c standard, will receive a exchange premium of up to €10,000. If the customer chooses a “Junger Stern” pre-owned car, the incentive can go up to €5,000. Customers who buy a new van with the exhaust gas Euro 6 Standard will receive an exchange premium of up to €6,000. If they choose a “Junger Stern” pre-owned van, the incentive can go up to €3,000. You can find further details about the exchange program both inside and outside the priority regions here.

Daimler is making a significant contribution to the German government’s concept in order to avoid any disadvantages for drivers of diesel-powered cars.

d. Mobility fund

We have significantly increased our planned contribution to the German government’s 2017 mobility fund ("immediate action program for clean air"): Together with BMW and Volkswagen, we are now providing the automobile industry's entire share of €250 million in full. We regret the fact that no other manufacturers have joined the program to date.

e. Local measures

The German Association of the Automotive Industry (VDA) is supporting the clean-air measures implemented by cities and municipalities in Germany. Daimler is taking part in these discussions, as are the other automotive manufacturers. They are particularly aimed at implementing measures to optimize the flow of traffic, to check on the expansion of an e-charging infrastructure and to continue the networking and digitalization of transport.

With local measures Daimler is focusing in particular on Stuttgart. Thus, for example, we are subsidizing our employees to use public transport such as the local tram and train network or buses to get to work. On days with high particulate matter readings, Daimler supports its employees who come to work via commuter train, streetcar or bus. Starting on October 15, 2018, during days with high particulate matter readings Daimler will take over the costs of its employees’ travel to work, as well as business trips, on local public transportation in the Stuttgart region. In addition, the company is offering a digital mobility solution via app for this program. Stuttgarter Straßenbahnen AG (SSB), the public transport company of the city of Stuttgart, is Daimler’s partner in the program. On days with high particulate matter readings, Daimler also does not conduct any test drives in Stuttgart. Car2go offers discounted prices for the use of an all-electric smart fortwo on days with high particulate matter readings.

A new Group initiative, entitled F.L.O.W., bundles all these measures together and is also developing additional planned or already piloted projects into new mobility concepts for Daimler employees. F.L.O.W. stands for “Fortbewegung, Lebensweise, Ökologie und Wirtschaft” (transport, lifestyle, ecology, and business). In the future, Daimler employees will also have the opportunity, using the “Flex Location” app, to reserve a workplace in a Daimler location nearer to their home, in order to help relieve congestion within the Stuttgart urban area. The aim is to get other companies, cities, and municipalities to join the F.L.O.W. initiative in the future.

3. Electric mobility and mobility services are making inroads

We aim to further improve the combustion engine and, in parallel, are championing hybrid technology. However, it is also clear that even better than low emissions are no local emissions at all. That is why we are going full speed ahead with electric mobility, and the technical and commercial opportunities now exist for us to do so:

The energy density of batteries is increasing. At the same time, production costs are decreasing. By 2025 an e-drive system could cost roughly the same as combustion drive. And we want to drive this forward, with e-vehicles that customers don't have to buy, but choose to buy because they are attractive. To this end we will be investing more than ten-billion euros over the next few years in extending and developing our electric fleet.

By 2020 we will be offering at least one all-electric option in every Mercedes model series. And by 2020 in both Europe and the U.S., we will make smart the first car brand to have moved its entire model range over to electric drive. E-mobility is a big issue for our commercial vehicles, too: Mercedes-Benz Vans is working on the electrification of all its commercial model series. The first of these will be the eVito in 2018; followed by the eSprinter in 2019.

Daimler has been gathering experience with electric trucks since 2010, and last year it launched its first series-produced fully electric truck — the Fuso eCanter light truck — on the market and delivered it to customers. In addition, the fully electric eActros for heavy-duty distribution transport has been proving its worth on Germany’s roads since June 2018. In September, Mercedes-Benz Trucks handed over the first of ten eActros trucks of the “innovation fleet” to a customer for day-to-day operations. Series production in the bus segment began in the fall of 2018. The first Mercedes-Benz eCitaro was recently delivered to the local public transportation provider of the city of Hamburg — Hamburger Hochbahn AG.

Even though it is sometimes claimed that the German automotive industry wishes to hold on to the status quo rather than drive change, the reality at Daimler is very different: No other automotive manufacturer worldwide registered as many patents in 2016 as Daimler: 2,175 in total, including 761 for CASE themes connectivity, automated driving, mobility services, carsharing, and e-mobility. Within the passenger car area we have more than doubled our investment in research and development since 2010, while investment into the above-mentioned “future fields” has increased fourfold.

By 2022 Mercedes-Benz will have brought out 10 fully-electric cars on the market.


There are many more measures that can be taken to further reduce nitrogen oxide in the short and medium term that make significantly more sense than introducing driving bans: Taking the development of state-of-the-art combustion engines even further, while, at the same time, pushing electric mobility and new forms of mobility; providing software updates for diesel vehicles in the field; improving traffic flow in cities; closer collaboration between municipalities, suppliers and automotive manufacturers; and the electrification of local public transport and local delivery.

As a car and commercial vehicle manufacturer, we are also working to keep people mobile and to deliver them the goods they need on a daily basis.

Note: This article was last updated in November, 2018.

¹ The values stated are the "NEDC CO2" measurements, within the meaning of section2 (2) of the Implementing Regulation (EU) 2017/1153, which were determined in accordance with appendix XII of Regulation (EC) No. 692/2008. The fuel consumption figures were calculated based on these values. Due to statutory changes to the relevant test processes, higher values may be entered in the vehicle's relevant certificate of conformity for vehicle registration and road fund purposes. The figures are not based on an individual model and do not constitute part of the product offer; they are provided solely for purposes of comparison between different vehicle models. Values will vary, depending on the optional extras selected.

² The remaining models are certified according to the Euro 6c Standard.

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