Jun 13, 2019 OEM
Significantly reduced NOx emissions are a characteristic feature of vehicles which are certified according to the Euro 6d-TEMP standard, and all new Mercedes-Benz passenger cars now meet this requirement.
Furthermore, Mercedes-Benz currently has a whole series of vehicles on the market that already comply with the even stricter Euro 6d standard. This will gradually become mandatory as of 01.01.2020.
Mercedes-Benz has said that its decision, made at the start of the decade, to develop an entirely new diesel engine generation is paying dividends. With the changeover to the new engine generation, all new Mercedes-Benz passenger cars available to order now comply with the Euro 6d-TEMP or Euro 6d standards.
The limit values for NOx in emission tests – for Euro 6d these are also at 80 milligrammes per kilometre also during RDE (Real Driving Emissions) tests – are so-called “not to exceed” limit values that must be complied with during each valid RDE test. This means that a vehicle may also not exceed the limit under the worst conceivable combinations of RDE conditions – for example, with a heavy load, in hilly topography, and in unfavourable temperature and traffic conditions. The limit applies not only to new vehicles but also to vehicles with more than 100,000 kilometres. Results of real-world tests on the road often stay significantly below the limit of 80 milligrammes per kilometre, which is confirmed by independent measurements.
The ADAC reported about its own extensive measurements in February 2019: “The NOx emissions of current cars are far below the test bench limits in real-world driving on the road”. The Mercedes-Benz C 220 d (combined fuel consumption 4.8 l/100 km, combined CO2 emissions 126-117 g/km) performed particularly well; “its NOx figure was hardly measurable between zero and one mg/km”.
Such individual measurements illustrate that the NOx challenge can also be solved technically for diesel-powered vehicles with the new engine generation. However, the average emissions of a vehicle over many thousands of kilometres are much more meaningful in this regard: Mercedes-Benz passenger cars equipped with the latest diesel technology achieve average figures of 20 to 30 mg of NOx per kilometre under RDE conditions.
When it comes to the nitrogen oxide emissions of diesel vehicles from different manufacturers, the ADAC finds: “Euro-6d-TEMP diesels emit 76 percent less NOx on average than Euro-6b diesels and 85 percent less than Euro-5 diesels. Random sample measurements on the road have shown that the emissions reduction of good Euro-6d-TEMP diesels compared with average Euro 5 diesels is even 95 to 99 percent”.
Thanks to the near-engine installation, the emission control system has low heat losses and thus very favourable operating conditions in the vast majority of operating situations. Further measures include:
- high and low-pressure exhaust gas recirculation including cooling
- a diesel oxidation catalytic converter (DOC) to avoid the emission of carbon monoxide (CO) and unburned hydrocarbons (HC)
- a particulate filter for capturing soot particles with combined SCR catalyst function (sDPF),
- an SCR catalytic converter (selective catalytic reduction) for reducing nitrogen oxides. For this purpose, ammonia in the form of the carrier AdBlue is mixed in with the exhaust gases and conditioned before entering the sDPF
- an additional underfloor catalyst (SCR) with ammonia slip catalyst coating (ASC).