Exhaust emission standard: What Euro 7 and Euro 6e mean for new cars
Cars with combustion engines are facing a major challenge with the Euro 7 emissions standard. Before that, the Euro 6e standard will be introduced.
With the Euro 7 emissions standard, passenger cars with internal combustion engines will probably have to do even better in the cold-start phase. It will come into force in 2027 at the earliest. For this reason, there is still an intermediate step: Euro 6e.
(Bild: VW)
- Christoph M. Schwarzer
(Hier finden Sie die deutsche Version des Beitrags)
On 12 October 2022, the European Commission will publish the proposal for the Euro 7 exhaust emission standard. Perhaps this will be the last specification for limiting emissions from internal combustion engines: From 2035 onwards, no new passenger cars may be registered that emit carbon dioxide. Euro 7, however, is mainly about limits for nitrogen oxides and particulates. As the limits are not expected to come into force until 2027 at the earliest, there will be an intermediate step: The current Euro 6d emission standard will be followed by Euro 6e.
The negotiating circles are silent. What is known so far is that the CO₂ emissions, which are relevant for the fleet limits, the nitrogen oxide emissions (NOx) and those for particulate matter (PM) and particle number (PN) are recorded in the WLTP driving cycle, i.e. on the laboratory test bench. In addition, and this is also not new, the exhaust emission limits must be complied with in road tests.
Emissions budget in the RDE
The road test - abbreviated RDE for Real Driving Emissions - is revised for Euro 7. Instead of defining a limit value in milligrams per kilometre (mg/km), there is an emissions budget for a distance of 16 kilometres. Specifically: In a strict scenario, a total of 320 mg of NOx may be emitted. This corresponds to 20 mg/km. In another scenario, 480 mg are discussed, which is arithmetically 30 mg/km. A decision has not yet been made public.
What is clear, however, is where the challenge for diesel engines and petrol engines lies: In the cold-start phase. Diesel engines currently often have two SCR catalytic converters (for Selective Catalytic Reaction) with urea injection to render nitrogen oxides harmless. A smaller one that heats up more quickly and a larger one for the long haul. In future, it may also be necessary to preheat the SCR catalytic converter(s) electrically - with consequential costs for the battery and alternator. Diesel cars in the premium segment often have a 48-volt mild hybrid system; here the basis for an auxiliary heater is already present.
(Bild: VW)
Petrol engines emit particulates because of the direct injection that is usually present. A filter is now a matter of course. However, this part of the exhaust gas aftertreatment has to become more efficient, which in turn costs money.
150 euros more in the compact car
"A small car with a petrol engine could achieve drastic emission improvements with an additional cost of 150 euros," says Felipe Rodriguez of the International Council on Clean Transportation (ICCT). He is confident that "the last generation of combustion engines can be made much cleaner" with little money. The Euro 7 emissions standard, says the ICCT, could prevent the premature deaths of 35,000 people.
(Bild: VW)
The nominal limits for nitrogen oxides and particulates have remained virtually unchanged on paper since the type approval date of 1 September 2014. But the conditions under which these limits must be complied with have been drastically tightened. Thus, cars with petrol engines are allowed to let out a maximum of 60 mg of nitrogen oxides per kilometre. For cars with diesel engines, the limit is 80 mg. These values must now also be met in the real-world road test RDE. The Euro 6d currently in force has a legally permitted tolerance here: the so-called conformity factor (CF). It is currently 1.43. In fact, cars are allowed to exceed the laboratory limit value by this amount.
Margin error instead of conformity factor
This is the point at which the Euro 6e emissions standard comes into play. It will apply to type approval from 1 September 2023 and one year later to all newly registered passenger cars. The conformity factor will be replaced by the PEMS error margin, which translates as an error tolerance for the mobile measurement systems in the road test. PEMS stands for Portable Emissions Measurement System.
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This PEMS error margin is really nothing more than a renaming of the Conformity Factor. For nitrogen oxides, an error margin of 0.1 comes into effect. For the particle number PN, the error margin is 0.34, which corresponds to a conformity factor of 1.34 and thus a tightening compared to the currently valid 1.5 for the particle number.
(Bild: Toyota)
Euro 6e with additional tightening
From the type approval date of 1 January 2025 and one year later for all newly registered passenger cars, Euro 6e will be revised again: The standard temperature at which the road tests are conducted will probably be changed. The exhaust gas aftertreatment must then comply with the limit values in a larger temperature window than in the first version of Euro 6e.
While the Euro 6e has been decided, the Euro 7 is still being debated. The Commission's proposal is by no means adopted with the publication date of 12 October 2022; after that, negotiations will begin. This much can be speculated according to current estimates: Cars with combustion engines will become marginally more expensive. However, new cars with petrol or diesel engines will only be threatened with extinction when CO₂ emissions are reduced to zero in 2035.
(mfz)