What are Euro 7 emissions regs and what will they mean for cars?

Audi Q3 in Mahle Powertrain's cold chamber

Detailed analysis of the latest updates to EU7 to show how the next generation of emissions regulations are shaping up

Much has been written about the political wrangling over the next step in European Union exhaust emissions regulations, Euro 7 (EU7).

The much-delayed suite of rules, already five years in the making, will shape the final generation of European ICE powertrains before the EU ploughs single-mindedly towards a 2035 ICE ban.

Significantly, the scope of EU7 has transformed from an incremental “cleaning up the air” to a radical “cleanest air possible”. In the process, it sets very tough pollutant limits and includes new gases and particles in the tests, requiring new measuring equipment to be developed.

The scope of testing will be extended dramatically, in the laboratory, on the road and in service. Live monitoring of pollutants over the car’s complete lifetime is due to replace on-board diagnostics as the guardian of a car’s compliance with the limits.

The fine detail of EU7 is still subject to negotiation, and Autocar understands that the 20 July publication date of the final legislation has been delayed to 30 November to allow for further fine-tuning.

There are signs that some of the more aggressive limits, put forward by the EU’s Consortium for Ultra-Low Vehicle Emissions (Clove), might be watered down, for example.

One suggestion is that EU6e regulations might be a sufficient step to clean up the final generations of ICE engines, as the uptake of BEVs is going faster than expected, making the more expensive elements of EU7 poor value for money in the race to clean up Europe’s air.

But what is the technical content of EU7? Autocar has teamed-up with Northampton-based Mahle Powertrain for a full run-down of the EU7 proposals.

*Timeline*

EU7 is expected to affect cars built for the 2027 model year, seven years after the legislation was first discussed and two years later than originally envisaged, as the scope of the regulation has been considerably widened, and the forensic detail of the regulations is pushing ICE technology and powertrain engineering/testing to its limits.

In the meantime, further updates will be made to EU6, with EU6e confirmed for September 2023.

*Pollutant Limits*

Have been a source of heated debate, with the EU generally pushing for lower numbers than the automotive industry.

At the heart of EU7 are two different proposed sets of aggressive targets – both challenging for the industry – that the EU has put on the table for negotiating purposes.

For example, on NOx, the EU is suggesting two possible reductions from the EU6d level of 60mg/km: a far-reaching drop to 20mg/km or a slightly less radical 30mg/km, while the industry is proposing 35mg/km.

CO is heading for a big drop, too, hence the talk of electrically heated e-catalysts, expected to be much bigger in size and more expensive, thanks to a higher content of platinum, palladium and rhodium.

Current limits are 1000mg/km, but the EU proposal is 400mg/km, while the industry proposes 500mg/km.

A significant consideration for both sides, however, is the real-world speed at which new engines can practically be put into production to EU7 standards and whether making the limits too difficult to implement will actually slow down progress to clean air.

*Particle number*

Particle number will be how EU7 addresses inner-city air quality, to tackle the issue of particles from brake dust possibly outstripping tailpipe emissions under EU6d.

EU7 will measure tailpipe emissions down to a smaller size of 10nm particles (currently 23nm) and significantly reduce the number allowed to be emitted.

The industry agrees that the number should be reduced dramatically, but there remains a debate over how far to go, especially since adding smaller particles to EU7 is estimated by some sources to increase the number measured by 30%.

*Additional pollutants*

A significant function of EU7 is to regulate a number of pollutants for the first time: methane, formaldehyde, nitrogen dioxide and ammonia gases.

“This is a huge volume of work for the OEMs to add in a short period of time from design, analysis, development, calibration and testing both in lab and on the road,” said Mahle.

*Sensors*

The race is on among tier-one suppliers to productionise new, affordable sensor components to measure EU7 pollutants to the accuracy required, including gases that have never been measured in a production car before.

This is vital, because the new on-board monitoring (OBM) regime in EU7 (see below) will be built around these components, which in EU6 spec engines cost just $10 per car. Because the sensors aren't yet available, engine-development programmes can't yet be run to final production standard.

*Real Driving Emissions testing*

On-road testing was introduced for EU6 to reduce NOx and PN emissions and is conducted with PEMS, an on-board rig. Adding extra pollutants into EU7 means additional measurement technology will have been added to the rig, increasing its size, weight and cost by at least 25%.

The gases can be measured in the lab, but as of today, a miniaturised PEMS analyser for the new gases doesn't exist in production, being at only the prototype stage.

An EU7 powertrain will also be tested to a much wider range of atmospheric conditions. The ‘normal’ test temperature is increasing from -7deg C to 35deg C (currently 0 to 30deg C), and the ‘extended conditions’ are rising from -7/38deg C to -10/45 deg C, meaning more expensive dyno testing in cold/hot chambers and real-world testing.

“As proposed, EU7 is expected to involve increased testing at the extreme boundary conditions,” said Mahle.

The industry will also bear extra costs for the equipment, with investment up in the near term, while the service life for equipment bought will be shorter, given the push to 0g/km by 2035.

There are also proposals for new operational tests, such as towing and repeated fast-acceleration tests, although whether the air quality benefits are worth the extra costs of these ‘edge’ cases is still being discussed.

*On-board monitoring*

EU7 is expected to move to a new regime of on-board monitoring (OBM), with real-time measurement of gases and pollutants.

If OBM detects out-of-limit emissions, a dashboard light will warn the driver and force a visit to a maintenance workshop, whereas EU6 links OBD to failure of specific components, for example the oxygen sensor.

“This is the most significant challenge of the EU7 proposal, due to changes in methodology of vehicle fault diagnostic and the lengthy time needed to test and validate,” said Mahle.

Because of this new in-service testing regime, Mahle has built new software tools for OEMs to speed up development of on-board monitoring.

In practice, an EU7 powertrain will have to remain completely within limits at all times of operation, over any driving cycle and a longer service life of the vehicle, with live monitoring of actual pollutants.

For EU6, an engine must maintain emissions durability over 160,000km, but EU7 is expected to extend that to 240,000km or 15 years.

*What does it mean for the motorist?*

Some car makers are already preparing for EU7 by reducing the number of lower-cost models, which the extra cost of the testing regime, the e-catalyst and other componentry are poised to make uneconomic.

Volkswagen, for example, has cancelled the next-generation Volkswagen Up family, while Citroën and Peugeot pulled out of their joint venture with Toyota for future C1 and 108 replacements.

The cost of developing EU7 engines must surely be a contributory factor in Mercedes-Benz’s recent talk about shifting up-market and culling its more affordable models, like the A-Class. It has already sold half of Smart to Geely, for example.

Extra costs of complying with EU7 are also highly likely to reduce ICE powertrain choice, as higher development costs will have to be spread over higher production volumes, making small runs of engines uneconomic.

It's also likely to hasten adoption of EVs as manufacturers drop some ICE models and bring forward EVs in their place, of course, but only if battery-cell and computer-chip supply chains can be scaled up fast enough.

Dashboard lights for out-of-limits engine emissions are also likely to become more common, as the new on-board monitoring regime widens the scope of faults and forces cars into the workshop for adjustment and repair more regularly, especially if new OBM sensors and software, developed in minimal time, prove temperamental in use.

Undoubtedly, car makers will attempt to limit the cost burden on buyers, but it feels inevitable that hiked-up design and development costs, pricier e-catalysts and additional sensor componentry will push up prices.

Given that every manufacturer's pot of development cash is being stretched in two directions (new EU7 engines and EV platforms), the scope for spending on brand-building niche models might well be curtailed for at least three to five years until cost bases return to a lower level.