Features
24 avr 18

Do you know your Euro 6 from your 6c and 6d-TEMP?

All new cars are Euro 6, but some are more Euro 6 than others. The letters following the number 6 (i.e. b, c or d) are indicative of the fact that they comply with the very latest version of the emission standard or not – and indeed face a possible ban from low-emission zones, or a (more or less) carefree future.

Update May 8, 2019: EVAP and ISC added (see below)

Between Euro 1 (1992) and Euro 6 (2014), emission limits have come down step by step, with different thresholds for petrol and diesel engines being introduced with the arrival of Euro 2 in 1996.

Source: Wikipedia

Since 2014, Euro 6 has been updated - and it will continue to be updated over the next years. Why is the EU calling these updates Euro 6c, 6d-TEMP and 6d rather than continuing counting and name the latter Euro 7, 8 and 9?

The answer lies in dieselgate, or rather: the fact that independent tests revealed dramatic discrepancies between NOx emissions measured in lab conditions – for type-approval purposes – and real-life measurements.

Euro 6c: WLTP

The emission limits set by Euro 6 in 2014 – not only for NOx, but also for particulate matter (PM) and all other toxic emissions – have remained the same, even though there are “updates”, indicated by the letters b, c and d.

These limits are valid for the tests performed in lab conditions in order to type-approve a car. Since September 2017, the tests concerned are carried out on the basis of WLTP rather than the outdated NEDC. That is why Europe changed the name of the standard from Euro 6b to Euro 6c. In other words, the standard hasn't changed, but the measuring method has.

However, along with WLTP came RDE (for Real Driving Emissions), a test carried out on public roads to make sure 'reality' matches 'controlled environment'. It is this RDE that imposes intermediate steps towards a truly new emission standard – indeed, Euro 7, which is likely to come into effect in the mid 2020s.

Euro 6d-TEMP and Euro 6d: RDE

Reality shows that OEMs have a hard time to close the gap between real (RDE) and lab (WLTP), especially in terms of NOx emissions. To cut them some slack, Europe allows a deviation between RDE measurements and WLTP measurements. In a nutshell: Euro 6c is the standard for WLTP measurements, while Euro 6d-TEMP and Euro 6d are the ones for RDE measurements.

Euro 6c (WLTP, i.e. lab conditions), which took effect on September 1st 2017 for new type approvals and is mandatory for all new cars from September 2018 onwards, means that NOx is limited to 60 and 80 mg/km for petrol and diesel, respectively. Euro 6d-TEMP (RDE, i.e. real driving conditions), which also took effect for new type approvals on September 1st 2017 but gives existing models time until September 2019, allows a deviation of 110 percent. This is the so-called conformity factor of 2.1.

Indeed, as a temporary measure (hence Euro 6d-TEMP), petrol cars can emit 126 mg/km while tested on the road, diesel cars 168 mg/km. By 2020, when Euro 6d takes effect, the allowed deviation between RDE and WLTP is reduced to 43 percent (conformity factor 1.43). Petrol cars must then stay below 85.8 mg/km, diesel cars are to keep their NOx emissions under 114.4 mg/km. 

Conformity factor under discussion

There is some controversy around the 2.1 conformity factor, that cuts OEMs some slack to adjust to the new RDE type approval procedure. It came into being in 2016, when the European Commission voted an amendment to the Euro 6 standard allowing NOx emissions measured during the Real Driving Emissions (RDE) test to deviate 110% from the 80 mg/km lab limit.

In December 2018, the General Court of the European Union ruled the Commission had no such power and as technologically difficult it may be for carmakers to meet the 80 mg/km limit in real-life conditions, that does not justify the leniency. The Commission has now appealed the court decision. If anything, it does not help customers to regain faith in diesel.

Which cars are already Euro 6d-TEMP or Euro 6d?

Basically every new model that has been type-approved since September 2017, plus existing models that have already made the switch ahead of the general introduction of Euro 6d-TEMP in September 2019. You can find a list of these vehicles here.

Some manufacturers even succeed in complying with the future Euro 6d standard. Even though electrification is central in Daimler’s and JLR’s PR discourse, both OEMs have invested considerably in diesel and believe it has a place now that NOx emissions are under control.

WLTP, NEDC correlated, RDE in a nutshell

Things are indeed complicated, but our video "WLTP: 7 questions and 7 answers" and "WLTP, NEDC, NEDC correlated, RDE: what's it all about" explain what to expect and how it impacts company car drivers, fleet managers, OEMs and leasing companies.

In case you were wondering whether real-world NOx emissions are really lower since the introduction of Euro 6d-temp: recent data shows that NOx emissions on the road have been reduced by 99 per cent.

Keep calm and diesel on?

That's a very good question. Click here to read our analysis. OEMs need diesel to achieve the EU-imposed 95 g/km CO2 target by 2021, but reverting to diesel alone won't cut it. Only massive electrification can save them from having to pay monster fines.

The next phase: Euro 6d-Temp EVAP and ISC

Just when you think things cannot become more complicated, Europe introduced an amendment to the Euro 6d-Temp emission standard requiring OEMs to measure evaporative emissions (EVAP) during 48 hours and to verify the actual emissions of cars when they are in service (In Service Conformity, or ISC) during five years or 100,000km.

What this means in practice and how it will effect consumers and businesses? Find out in our article: Amended Euro 6d: EVAP and ISC could cause homologation delays.

Picture copyright: TÜV Nord, 2018

Authored by: Dieter Quartier