Mercedes clarifies its stance in the wake of new Dutch environment agency emissions findings
Jim Holder
4 February 2016

Real-world tests have recorded the Mercedes C-Class C220 TDi BlueTec emitting 40 times more NOx than the legal limit in laboratory tests. However, Mercedes says the results are a consequence of real-world tests not reflecting official procedures, primarily because of the low ambient temperature during the test.

The tests were conducted by Holland’s Organisation for Applied Science Research (TNO) on behalf of the Dutch Minister of the Environment.

Mercedes says the discrepancy is partly down to the exhaust gas recirculation (EGR) process operating differently between five and seven degrees centigrade, a process it says is aimed at protecting the EGR cooler. Official laboratory tests that define whether a car is legal are conducted at 22 degrees centigrade.

Mercedes says this practice is fully legal, and that it is required to ensure the regulated requirement of delivering full functionality of the exhaust gas after-treatment system up to at least 160,000 kilometres. However, critics, while accepting the legality of the system, have suggested that such a device should be banned as it means the cars are hugely more polluting in low temperatures.

A Mercedes statement read: “Daimler AG once again absolutely rejects the inherent accusation of manipulation. Mercedes-Benz vehicles fully comply with the national regulations in force at the time of vehicle registration.

“We absolutely reject speculation or interpretation that possible deviations between test-bench measurements and measurements made during real driving conditions can only be explained by manipulation. No defeat device, ie a function that improperly restricts the effectiveness of exhaust-gas after-treatment, is used by Mercedes-Benz. Neither do Mercedes-Benz vehicles have a function that automatically recognises when a vehicle is being tested.”

However, as a consequence of the claims, a pressure group in Germany, Deutsche Umwelt Hilfe, has called on Germany’s automotive regulator Kraftfahrt-Bundesamt (KBA) to withdraw the EU-wide type approval for all diesel-powered C-Class models, or have the cars banned from all inner cities when temperatures drop below 10 degrees centigrade.

If type approval were withdrawn, affected cars would have to be taken off sale.

Our Verdict

Mercedes-Benz C-class
The C-Class shares a lot of its looks with the new S-Class, furthering its desirability

Can our perennial runner-up in this class finally reach the top spot?

Join the debate


4 February 2016
I wouldn't call anything below 22c a low temperature. It's probably well above the year average in most environments. Best be on the safe side and ban diesels now

typos1 - Just can’t respect opinion

4 February 2016
xxxx wrote:

I wouldn't call anything below 22c a low temperature. It's probably well above the year average in most environments. Best be on the safe side and ban diesels now

Funny that never mention in your anti diesel rants that petrol cars emit up to 28 times the amount of deadly CO as diesels do. Also petrol catalysts in the cold weather take ages to work and often do not work at all on short town journeys like the school run.

4 February 2016
Just shows that despite being much better than their predecessors in theory and practice diesels are still polluting and that EU lost the plot a long time ago in promoting them so much.Sure US is the opposite with gas guzzling trucks etc.Also the enemy of good performance of cars is weight,just as people have become more Obese so have cars.Anything over 1500 KG should be avoided,as should diesels.



4 February 2016
....I am totally with you on this one madmac, time for this adulation of diesel to end and for cars to reduce weight.

4 February 2016
Of course it's manipulation! They have fitted pollution control equipment designed not to work at low temperatures. I understand the engineering reson for this (why sacrifice reliability for something that will not show up in official test data) but it's pretty unethical behaviour. I can't remember Mercedes ever admitting that their cars emit more pollution at low temperature. Ban diesel from cities - it is the only way.

4 February 2016
All products should be sold measured against Health. Imported toys painted with the wrong paint or dangerous parts are quickly pulled. If cars on sale prevent clean air targets being met then on moral if not legal grounds they should be banned. Governments quickly ignore their first priority which is the protection of citizens. I think it is disgraceful that we don't meet these clean air targets in some of our cities.

4 February 2016
It states that the system works differently at below 5-7 degrees centigrade not just below 22 and this is the same for all cars petrol and diesel. The reason is as Mercedes-Benz states which is to prevent damage caused by the Egr cooler getting chocked up with carbon deposits as the cold air cools it to quickly. The European union knows this and it is perfectly legal and always has been. The big question is whether the nox is as bad as It's being made out to be. Levels were way higher years ago and I doubt the amount of deaths being attributed to it are true. A big problem is how to find a group of people that have never been exposed to it and test them,of course they don't exist and even if they did how can you rule out the other environmental exposure they have had being the cause. There is a lot of people who have a vested intrest in this making a lot of noise.
K. M

4 February 2016
How fast people went from going on about how much clearer the air was to the idea that you take your life into you own hands with every breath. No one has bothered to investigate the rationality over how the required numbers were arrived at in the first place and what the true benefits have been, if any. It would appear that the efforts to drive up the costs of ownership based on these supposed figures and their benefits are now found to be faulty at best and a lie at worse yet here we have people, supposedly car lovers, practically begging for the death of the internal combustion engine that is still the best means to propel a vehicle based on capacity and ease of use. The drive to save the planet and its people have led to numbers being created from thin (and apparently heavily polluted) air and increased weight of cars so that everyone can survive a collision rather than avoiding the collision in the first place. Unless you have a wholesale counter-assault against the politicians and Leftists you will find yourself in the next generation where you modes of transport will be either walk, bike or take a government-run entity to where you are going (train, bus, etc.). Once people realize the ultimate aim is to limit and control the mobility of the masses then we can start the process of fixing the mess we collectively how allowed our global transportation policies to become over the last 20 years.

4 February 2016
@Moparman wow you've got a vivid imagination.
What's clearly needed is realistic vehicle testing. Once this happens electrification will accelerate.

4 February 2016
Are you from the West Coast USA?


Add your comment

Log in or register to post comments

Find an Autocar car review

Driven this week

  • Mercedes-Benz E-Class Estate
    First Drive
    19 March 2018
    The Mercedes-Benz E-Class could be all the estate car you’ll ever want — or it could be overkill. Let’s see which...
  • Dallara Stradale
    The Stradale is the first road-legel car from Italian motorsport constructor Dallara
    First Drive
    16 March 2018
    The motorsport constructor's first road car is inspired by Lotus minimalism. Does it thrill on road and track?
  • Hyundai i30 N
    Standard spec is good so paint colour is our car’s only option
    First Drive
    16 March 2018
    What’s Hyundai’s first hot hatch and N-brand debutant really like? Let’s find out
  • Porsche Boxster GTS
    This is the new GTS version of the Porsche Boxster
    First Drive
    15 March 2018
    The 718-generation Boxster is our favourite roadster of the moment – so is this new GTS variant worth the extra outlay?
  • BMW 5 Series
    First Drive
    15 March 2018
    The BMW 5 Series is top of the mid-exec pack, but is there still room for a diesel saloon in everyday family life?