Euro 6 emissions standards: what do they mean for you?

Diesel smog, haze, pollution
24 Sep, 2015 1:00pm Chris Ebbs Martin Saarinen

All new cars sold must meet Euro 6 standards for exhaust emissions of NOx and other pollutants

Manufacturers and vehicle emissions standards are often under the microscope. The issue usually revolves around how accurately tests and manufacturer's figures reflect real world driving standards - and whether or not they can be trusted. 

To keep up to date on the latest standards and procedures, we've compiled a guide highlighting the latest testing standards and new proposals to improve them, as well as explained how the current Euro 6 standard for diesel cars works. 

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Currently all EU and UK cars are tested via the new European driving cycle (NEDC) procedure, where emissions are measured under laboratory conditions on rolling roads. 

Government agencies act as witnesses to the testing, which is conducted in a controlled environment where the temperature, fluid levels and tyre pressures are all measured. To make it as accurate as possible to cars that motorists can buy, cars tested are randomly selected from the production lines, rather than supplied by the manufacturers. 

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To make emissions tests more reflective of real world driving, new testing procedures are currently under proposal to be introduced in 2017. 

The new proposals include an additional real world driving emissions (RDE) test for regulated pollutant emissions. The RDE is to be carried out on the road instead of the lab, and will use a portable emissions measurement system to record real world emissions. 

The RDE element is expected to introduce a more realistic and stringent approach to emissions testing in the future. 

What is Euro 6?

From September 2015, all new cars bought must be Euro 6 compliant. The aim of the Euro 6 EU legislation is to make cars cleaner. This means lower levels of harmful car and van exhaust emissions that you may not have heard of such as nitrogen oxide (NOx), carbon monoxide (CO), hydrocarbons (THC and NMHC) and particulate matter (PM), which is basically soot. The knock-on effects of reducing these can also mean better fuel economy and lower emissions of CO2.

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NOx is a harmful pollutant that is often blamed for damaging the environment but has also been proven to have serious health implications on the public. Particulate matter, meanwhile, is a local pollutant that has also been linked to health problems.

The new Euro 6 regulations set different standards for petrol and diesel cars. For diesel cars, they dramatically drop the permitted level of NOx emitted down to a maximum of 80mg/km compared to the 180mg/km level that was required for cars to meet the previous Euro 5 emissions standards. The limit for NOx from petrol cars remains at 60mg/km, the same as for the Euro 5 standard.

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Diesel cars and the Euro 6 emissions standards

In particular, it's older diesel cars that produce higher levels of NOx and particulate matter and these have come under fire from a number of environmental groups. Some have blamed the Government for enticing consumers into diesel cars with VED and company car tax structures that reward low CO2 emissions. Diesel cars tend to be better than petrol models when it comes to CO2 output.

The automotive industry and the Society of Motor Manufacturers and Traders (SMMT) that represents it have recently come out in defence of diesel cars and started a campaign to raise awareness of the clean diesel technology fitted to the new Euro 6 compliant models.

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The SMMT is attempting to make sure all diesel cars aren't tarred with the same bush by drawing a line between older diesel cars and the new generation of clean diesel models. The concern is that confusion could lead buyers to shun new Euro 6 diesel cars when they're virtually as environmentally-friendly as the petrol alternatives.

In the short term, the new Euro 6 emission standards, are unlikley to have a direct impact on motorists, though they could see fuel economy and emissions of new cars improve further as the latest engine and exhaust treatment technology becomes standard across the industry. 

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The longer term future for diesel cars looks a little more uncertain for the reasons touched on above and moves that are afoot within Government, at a local and national level, to penalise owners of diesel cars financially.  

Diesel cars have found themselves in the spotlight with London Mayor Boris Johnson calling for an Ultra Low Emission Zone in London be put in place by 2020 that would mean older diesel cars that don't meet Euro 6 emission standards would be charged an extra £10 to enter the capital on top of standard London congestion charge.

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Some councils have already started to charge owners of diesel cars more for parking permits. Islington council in London is set to introduce a surcharge of £96 for anyone with a diesel car from April 1 2015. It claims that the reasoning behind this is "to protect residents from the health risks associated with diesel emissions".

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Euro 1 to Euro 6: European emissions legislation timeline

European emission standards first came in to force in 1992 with Euro 1 standards becoming law. This initial standard ensured that diesel cars emitted no more than 780mg/km of NOx, while the maximum for petrol engines was 490mg/km. 

This moved on to Euro 2 in 1997 that dropped diesel NOx to 730mg/km and Euro 3 standards followed in 2000 lowering the diesel NOx limit to 500mg/km. By 2006, Euro 4 emissions were in place reducing the max NOx in diesels to 250mg/km and Euro 5 reduced it further to 180mg/km in 2009.

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Throughtout this time, the maximum amount of NOx emitted by diesel cars has been way behind that of petrol models. Under the new Euro 6 standards, however, the maximum level for NOx in diesel models is 80mg/km compared to 60mg/km in petrol cars.

Euro emissions standards for diesel cars 

Euro standard





Euro 1 July 1992 2.72  - 0.14 
Euro 2 January 1996 1.0 - 0.08
Euro 3 January 2000 0.64 0.50 0.05
Euro 4 January 2005 0.50 0.25 0.025
Euro 5a September 2009 0.50 0.180 0.005
Euro 6 September 2014 0.50 0.080 0.005

Euro emissions standards for petrol cars

Euro standard





Euro 1 July 1992 2.72  - -
Euro 2 January 1996 2.2 - -
Euro 3 January 2000 2.3 0.15 -
Euro 4 January 2005 1.0 0.08 -
Euro 5 September 2009 1.0 0.060 0.005
Euro 6 September 2014 1.0 0.060 0.005

What do you think about the environmental debate surrounding petrol and diesel cars? Have your say in the comments section below...