RAC Cars News


What Are Euro 6 Emissions Standards?

By raccars Published

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Car emissions are under a fierce spotlight at the moment, and the discrepancy between manufacturers' official figures and real world performance is gaining increasing attention as consumer trust in car makers reaches a low point. The VW emissions scandal rumbles on, leaving car owners wondering exactly what they are putting out into the air every time they use their car.

In Europe at least, car owners are being reassured by motoring groups that stringent testing ensures safe emissions levels. All new cars undertake new European driving cycle (NEDC) testing, which means they are laboratory tested using a rolling road to measure fuel economy and exhaust emissions. The tests are overseen by government regulators and the vehicles used are taken at random from manufacturers' production lines rather than supplied by the car maker.

After much criticism of the unrealistic laboratory testing environment, a new set of testing parameters comes into place in 2017. This means a new real world driving emissions (RDE) test is to be added, taking place on a real road instead of in the laboratory and using portable testing equipment to record emissions.

Euro 6 emissions standards came into force this month, designed to make the air around us cleaner by reducing the permitted levels of exhaust pollutants, including carbon monoxide (CO), nitrogen oxide (NOx), particulate matter (PM) and hydrocarbons (NMHC and THC). Different standards apply to petrol and diesel cars.

Diesel car emissions of NOx must now fall within 80mg/km - a dramatic reduction from the 180mg/km which was permitted under the previous Euro 5 regime. NOx limits for petrol cars remain unchanged at 60mg/km.

Older diesel cars and their high levels of NOx and particulate matter are the ones causing particular concern at the moment. NOx is believed to cause a number of health problems and environmental damage, while particulate matter is essentially soot, which is blamed for local pollution. However, motoring organisations are keen to point out that modern diesel engines are far cleaner and greener than they used to be, in an attempt to counter the rising tide of anti-diesel rhetoric which could impact diesel car sales. New diesels which are Euro 6 compliant are not really any less environmentally friendly than modern petrol cars and Euro 6 limits will help to spread the latest engine technology and exhaust treatments to become industry standard.

In the long term, diesel cars are facing an uncertain future. After years of encouragement and incentives to buy diesel cars, their owners are now being penalised at governmental level by extra charges. The ultra low emissions zone (ULEZ) set to come into place in London in 2020 will apply an extra £10 charge on older diesel cars to enter the city centre, on top of the existing congestion charge.

The first European emissions standard, Euro 1, was introduced in 1992. It set NOx limits of 780mg/km for diesels and 490mg/km for petrol cars. In 1997 these limits were updated by Euro 2, reducing to 730mg/km for diesel and to 500mg/km for Euro 3 in 2000. Euro 4 in 2006 further reduced the NOx limit for new diesel cars to 250mg/km, and again to 180mg/km for Euro 5 in 2009. Over the same time period, carbon monoxide and particulate matter limits have also been dramatically reduced.

Petrol cars are subject to a lower NOx limit but traditionally they are higher in carbon dioxide (CO2) emissions instead. CO limits for petrol have gone from 2.72 in 1992 to 1.0 by Euro 4 in 2005, compared to 0.5 for diesel. CO2 levels from petrol cars were the original environmental demon and led to the push for diesel, until later scientific research pinpointed NOx as a bigger danger.

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