The diesel debate: 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.

The German media and public are still debating diesel technology and driving bans. It goes without saying that we, as an automaker, bear responsibility in bringing individual mobility, climate protection, and air quality control into harmony. As a company that, for more than 130 years now, has demonstrated total commitment to helping people be mobile, we reject driving bans, which are a forced restriction on mobility. We are convinced that emissions of nitrogen oxides in cities can also be kept within limits — without driving bans and with the modern diesel engine. The objective reasons and technical facts supporting our position are given in more detail below:

We support the modern diesel engine as part of the drive-system mix of the future:

• Firstly, the diesel engine has not been a significant source of particulates for years now.

• Secondly, the new diesel engine generation already demonstrated how Mercedes-Benz can provide a technical solution to the NOx challenge posed by diesel cars in 2016. As a result of our experiences over the last few years, we can also improve the NOx emissions of many older vehicles both effectively and relatively swiftly using software updates.

• Thirdly, the improvement of diesel drive systems will greatly help us reach climate targets over the medium term because it reduces the amount of CO₂ from road traffic. As we progress toward electric mobility, the failure to use this technology would therefore be counterproductive for the climate as well.

In short, doing away with the diesel at this point in time would be a mistake, for both ecological and economic reasons.

1. NOx emissions are continuously decreasing thanks, in part, 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 being asked. However, in the diesel debate the impression is often given that nitrogen oxide (NOx) pollution in Germany has never been as high as it is today. In fact, the opposite is true. According to the German Environment Agency, the pollution caused by traffic has fallen by more than 70 percent since 1990, despite traffic volumes rising significantly during the same period. In other words, there has been a clear development: Traffic is increasing, and at the same time the air is becoming cleaner.

It’s clear that the limit values for NOx are still being exceeded at many monitoring stations located near road traffic. However, it is also a fact that since 2015 there have been no cases of NOx limit values being exceeded at the background monitoring stations inside cities.

In the public discourse concerning the air quality of inner cities, people continue to often lump particulate matter together with NOx. The problem of particulate emissions due to diesel engines proved solvable, however, thanks to the introduction of the soot particle filter. Mercedes-Benz first equipped diesel cars with such filters back in 1985. The lessons learned from this program formed the basis for the development of innovative and highly efficient filter technologies. At Mercedes, these filters have been standard equipment in diesel cars since 2005. We also install soot particle filters in most of our gasoline-powered cars. In fact, almost all of these vehicles in Europe have been equipped with a gasoline particulate filter since the summer of 2018.

Of course, there are still older vehicles being driven on the roads. Nonetheless, particulate emissions from engines are low by comparison with other sources. According to the German Environment Agency and the City of Stuttgart, engines are only responsible for less than 10 percent of the particulate matter emissions on the Neckartor road — one of the most heavily traveled roads in Germany. The sources of particulate matter are diverse and can differ widely, depending on local conditions. The main sources in Germany are agriculture, industry, construction work, small furnaces in private households, the raising of dust, and abrasion from vehicle brakes and tires.

However, the total volume of particulate matter emissions in Germany has continued to decrease in recent years. In Europe, the fine PM 2.5 emissions in the outside air have been subject to an annual average target value of 25 µg/m³ 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 violations 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 the year. Other than a single exception (at an industrial measuring station in Lünen), there have been no breaches of this limit for particulate emissions anywhere in Germany during 2018.

We believe that the positive trend in the figures for NOx emissions in particular will intensify substantially further in the near future. Three developments play an especially crucial role here: Firstly, vehicles with the latest-generation diesel engines are coming onto the market in ever greater numbers; secondly, more and more vehicles are being offered that are certified according to the latest emissions standards: Euro 6d-TEMP and Euro 6d. Thirdly, the measures that automakers and governments have initiated in recent years are now bearing fruit.

a. The latest generation of engines

Mercedes-Benz has been offering the crucial innovations in the further development of diesel technology in its series-produced vehicles since as early as 2016. For example, the four-cylinder OM 654 diesel engine — which combines close-coupled exhaust gas aftertreatment, stepped combustion bowls, and improved multiway exhaust gas recirculation — was introduced in the E-Class as early as April 2016.

Since then, Mercedes-Benz has been systematically restructuring its product portfolio in line with the new generation of diesel engines. In the process, the Group has invested approximately €3 billion in development and production. After the introduction 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 OEM 608 was installed in the new A-Class A 180 d starting in May 2018 (fuel consumption, combined: 4.5-4.1 l/100 km, CO₂ emissions, combined: 118-108 g/km)*. As a result, the new diesel engines from Mercedes-Benz are now available for all classes of automobiles, from compacts to the luxury segment.

Vehicles with these engines also have low NOx emissions in road operation. On many journeys using the Real Driving Emissions (RDE) measuring process, they even record values significantly lower than the current laboratory threshold limit of 80 milligrams. In its 13/2019 issue, the magazine auto motor und sport reports that (No. 13, June 6, 2019) emission measurements on twelve test vehicles from different brands resulted in the tested Mercedes C 300 d Wagon (fuel consumption, combined: 5.6-5.0 l/100 km, CO₂ emissions, combined: 147-133 g/km)* emitting “almost no NOx”. The article also mentions precise figures for the measurement results: “With a measly 13 milligrams of NOx, it goes to the top of our Mr. Clean hit list. Until recently, it seemed inconceivable that diesel engines could achieve such figures at all. […] However, the new two-liter diesel, designated OM 654, was systematically enhanced for reduced emissions. The NOx problem of many cities is therefore bound to be resolved as soon as more new cars are registered.”

This example shows that current vehicles which are equipped with the latest diesel technology can achieve NOx emission values on the road that in some RDE measurements are in a very low double-digit or even in the single-digit range.

The OM 654.

Such individual measurements illustrate that the NOx problem can also be solved technologically for diesel-powered vehicles featuring the latest engine generation. However, the average emissions of a vehicle over many thousands of kilometers are much more meaningful in this regard: Mercedes Benz cars equipped with the latest diesel technology achieve average figures of 20 to 30 mg of NOx per kilometer under RDE conditions.

Which key innovations made this substantial enhancement of diesel engines possible? The effectiveness of exhaust gas aftertreatment has been considerably increased in the new engines, thanks to the system’s close coupling with the engine and an improved exhaust gas temperature management system at low engine loads — in other words, low speeds. This has substantially boosted the system’s effectiveness in cities. The temperature range at which exhaust treatment is especially effective has been extended significantly in the new engine generation, without damaging any of the components. Average NOx values that are sometimes significantly below the laboratory value of 80 mg/km are therefore achieved in normal driving operation at low temperatures as well.

The German Technical Inspection Authority and DEKRA PEMS measurements made in 2016 at differing temperatures of the OM 656 and OM 654 diesel engines in Mercedes Benz vehicles. Even back then, the values were also significantly below the laboratory threshold limit of 80 mg/km and the RDE threshold limit for EU6d-TEMP (Stage 1) of 168 mg/km at low temperatures. The engine technology has been improved further since then.

And the new-generation engines still have potential for future improvements. We therefore assume that we will be able to reduce NOx emissions even further. Our goal for 2020 is to achieve average NOx emissions of around 30 milligrams per kilometer in Stage 2 RDE tests. In the years thereafter, we plan to average at around 20 milligrams. We are particularly striving to achieve these values for RDE tests in cities.

One of the ways we will achieve this is by steadily improving the interplay of the various components in the overall drive system — especially the highly complex engine control system. In addition, new and further-developed hardware will be introduced in the years ahead.

b. EURO 6d-TEMP certification

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. This has already been demonstrated by a study published in 2016 that was backed by the Federal Ministry for the Environment, the German Environment Agency, and the German Association of the Automotive Industry (VDA) among others. At Mercedes-Benz Cars, the entire fleet for Europe has been certified according to the Euro 6d-TEMP standard or better since June 2019. What’s more, we presented the new B-Class with a two-liter diesel engine and the new GLE with a three-liter six-cylinder diesel engine back in the fall of 2018 — the first models that already meet the Euro 6d standard. This has been made possible by the expanded exhaust gas aftertreatment system using an additional underfloor SCR catalytic converter. The number of models from Mercedes-Benz that are certified according to the Euro 6d standard, which will go into effect for new vehicle types on January 1, 2020, is steadily increasing.

The limit values for NOx in the emission tests — for Euro 6d these are also set at 80 milligrams per kilometer during RDE tests — are “not to exceed” limit values that must be complied with throughout every valid RDE test. This means that a vehicle may not exceed the limit under the worst conceivable combination of RDE conditions — for example, with a heavy load, in hilly terrain, and in unfavorable temperature and traffic conditions. The limit applies not only to new vehicles, but also to vehicles with more than 100,000 kilometers on the clock. Results of real-world tests on the road often stay significantly below the limit of 80 milligrams per kilometer, which is confirmed by the previously mentioned measurements conducted by external organizations.

2. The measures adopted at the “diesel summits” are effective

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

The measures at a glance:

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

2. Software updates for a large proportion of the Euro 5 and Euro 6 diesel vehicles in Europe.

3. Support of the German federal government’s clean air concept, with an attractive exchange premium for “junge Sterne” with diesel engines in the key regions which are defined by the federal government¹, 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 Euro 5 and Euro 6 vehicles in Europe, we announced even before the “first” diesel summit in August 2017 that we would extend our voluntary service measures involving software updates to over three million vehicles. The company has since then extended this campaign to other car and van models. Daimler has in addition been carrying out obligatory recalls — during which software updates are also applied — at the order of Germany’s Federal Motor Transport Authority (KBA) since 2018. 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.

In total, Daimler is developing several hundred software variants for the announced field measures. As is well known, Daimler began to apply software updates to Euro 6 diesel vehicles from Mercedes-Benz after this measure was initially approved in September 2018. More than 90 percent of these vehicles in Germany now have the updated software. Further field updates of Euro 5 and Euro 6 vehicles have been made since the beginning of 2019.

Many people may be wondering why we are able to improve the emissions of vehicles out in the field now and not before, and why these improvements have so clearly been achieved through software updates alone. There is also an explanation for this. Our developers work continuously to make the various components and functions interact more effectively. The same is true for the highly complex engine management system. We have made great progress in this area in recent years: To make these updates, our engineers have used the lessons learned from the development of the new diesel engine family, as well as experience from the field and the ongoing measures. This has allowed us to take many vehicles closer to their system limits without there being any corresponding risk to the quality of the vehicles.

b. Our position on hardware retrofit solutions

Following the governing coalition’s resolution, Daimler announced, in early October 2018, its participation in a hardware retrofitting program for diesel-powered vehicles in the defined priority regions. This program is being conducted as part of the German federal government’s concept for cleaner air and the safeguarding of individual mobility.

The company has promised to contribute a significant amount of up to €3,000 (gross) per vehicle as a grant in the defined priority regions in order to promote the approved retrofitting of hardware in diesel cars and vans with M1 certification (“passenger car certification”). It goes without saying that we will keep our promise.Daimler will not itself offer or install any hardware solutions for Euro 5 diesel vehicles, but instead leave this task to third-party retrofitting companies. To facilitate this process, we will supply the retrofitting companies with technical information about our vehicles.

The first group of providers has announced that it has obtained a General Operating License (ABE) from the Federal Motor Transport Authority (KBA) for the retrofitting of hardware to certain vehicle models from Mercedes-Benz. To make it as easy and efficient as possible for people to apply for the Daimler grant, we have set up a website (German language only) for this purpose at: This website also contains additional information about the topic.

c. 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 contributed our financial share in 2018 as agreed.

d. 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. The focus is on a range of measures, including optimizing the flow of traffic, looking into the expansion of an e-charging infrastructure, and continuing the networking and digitalization of transport.

With the local measures, Daimler is focusing in particular on Stuttgart. For example, we are subsidizing our employees’ use of public transport modes such as commuter trains, trams and buses, to get to work. On days with high particulate matter readings in Stuttgart, Daimler employees will, beginning on November 1, 2019, be able to use their plant ID cards to take public transport in the VVS tariff zone for free in order to commute to work and back and for business trips. Daimler will pay the costs of these journeys.

A Group initiative, entitled F.L.O.W., bundles all these measures together and is also developing other 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. Increasing importance of electric mobility

One thing is clear: We want to further improve combustion engines. Having no local emissions at all is, of course, even better than having low emissions. That’s why we are going full speed ahead with electric mobility, and now we also have the technical and commercial opportunities to do this. Batteries’ energy density is increasing.

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

At the same time, production costs are decreasing. By 2025, an e-drive system could cost roughly the same as a combustion engine system.

Daimler AG is greatly promoting the transformation of transportation systems to make emission-free mobility possible. In the car sector, we have specified our targets in a strategy titled Ambition 2039. As early as 2030, the company aims to have plug-in hybrids or all-electric vehicles make up more than 50% of car sales. By 2039, the fleet of new Mercedes-Benz cars should be CO₂-neutral. What exactly does that mean? It means our company will be thoroughly transformed within less than three product cycles. This is not a long period of time when one considers that fossil fuels have dominated our industry ever since Carl Benz and Gottlieb Daimler invented the automobile more than 130 years ago. But as a company founded by engineers, we believe that technology can help us shape a better future. Innovation will pave the way to sustainable mobility. And we want to be driving this forward: With e-vehicles that customers aren’t forced to buy, but choose to buy because they are attractive.

E-mobility is a big issue for our commercial vehicles, too: Mercedes-Benz Vans is working on the electrification of all commercial model series. The first of these was the eVito, in 2018; it was followed by the eSprinter in 2019. Daimler has been gathering experience with FUSO electric trucks since 2010, and last year it launched the FUSO eCanter light truck and handed it over to the customer. This vehicle is the first fully electric truck to be produced in a small batch . The all-electric Mercedes-Benz eActros for heavy-duty distribution transportation has proven its worth since September 2018, when Mercedes-Benz Trucks handed over the first of ten eActros trucks of the “innovation fleet” to a customer for day-to-day operations. In December 2018, the subsidiary Daimler Trucks North America (DTNA) handed over the first medium-duty Freightliner eM2 to a customer as the start of practical trials for medium- and heavy-duty electric trucks in the U.S. In August 2019, the Freightliner eCascadia for heavy-duty distribution transportation also began trials. Series production in the bus segment began in the fall of 2018. Only a year later, orders for the eCitaro have risen to a three-digit figure.

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: In 2016, Daimler registered in total 2,175 patents, including 761 for CASE topics connectivity, automated driving, mobility services, carsharing, and e-mobility. Within the car sector we have more than doubled our investment in research and development since 2010, while investment into the previously mentioned future-oriented fields has actually increased fourfold.


There are many other steps that can be taken to further reduce nitrogen oxides in the short and medium terms, and which make significantly greater sense than introducing driving bans. Taking the development of state-of-the-art combustion engines even further, while at the same time promoting electric mobility and new forms of mobility; applying software updates to diesel vehicles owned by customers and trade-in premiums¹; improving traffic flow in cities; closer collaboration between municipalities, suppliers, and automotive manufacturers; and the electrification of local public transport and short-radius distribution.

As a car and commercial vehicle manufacturer, we are also continuing to work to maintain people’s individual mobility, especially in cities, and to keep them supplied with the goods they need.

Note: This article was last updated in January 2021.


The diesel exchange bonus for new and demonstration vehicles expired on December 31, 2019. Offers for new or demonstration vehicles had to be concluded with an order by December 31, 2019. A delivery could then take place until December 31, 2020.

For the used vehicles - Junge Sterne - the exchange premium has ended with the order date on July 31, 2021. The maximum delivery date may be September 30th, 2021, which means that the deadline for submitting the application via the RetailPortal also ends.