Euro exhaust emissions standards explained

The issues of exhaust emissions be they actual pollutants, or carbon dioxide, is never far from the headlines.

For the typical everyday motorist, if influences not just your car tax rates but also where you can go. Clean Air Zones are appearing in an increasing number of British cities, which dictate whether, or not, you need to pay extra taxes to enter and this depends on the emissions standards that passenger cars met, when new.

What are Euro Emissions standards?

According to the Society of Motor Manufacturers and Traders (SMMT), the mandated Euro Emissions Standards have been responsible for slashing new vehicle hydrocarbon emissions in half, NOx by 84% and particulate matter by 96%. That was back in 2017 and so the contributions that this legislation has made to air quality is likely to have increased.

You will find your car's compliance standard listed on the V5C Registration Document. Your car wouold ont have been tested but a presentatiove model would have been, to allow it to be sold legally in the UK and EU. The list below gives an overview of when the legilsation apeared for new cars and an approximate introduction date. You may find the Euro bumber displayed in Roman numerals but the reference is the same:

Euro 1 (1993):

While emissions legilsation pre-dated the first Euro standard, Euro 1 kick-started regular and ever-tightening regulations. Euro 1's introduction mandated that new cars had to be fitted with catalytic converters and run on unleaded petrol. The prime aim was reduce hydrocarbons (HC), carbon monoxide (CO), hydrocarbons (HC) and nitrogen oxides (NOx). Only diesels had to meet particulate standards.

Euro 2 (1996):

This updated standard build upon the blocks set by Euro 1. It cut the CO, HC and NOx limits and commenced different limits set for petrol and diesels. By this time, many diesels were also fitted with catalytic converters.

Euro 3 (2000):

The new Millenium saw the CO and diesel particulate limits reduced still further. Diesels were also required to meet NOx targets, although these were still three times higher than the petrol limits.

Euro 4 (2005):

In the mid-naughties, Euro 4 saw these limits cut again for petrol and diesel, although petrol particulates continued to be unregulated.

Euro 5 (2010):

Euro 5 focussed more on particulate output. While direct injection petrol engines were good at reducing CO2, they produced higher levels of particulates. Therefore particulate levels especially were reduced, especially for diesels, where particiulate filters (DPFs) had to be fitted in order to comply.

Euro 6 (2014):

The main focus of Euro 6 was to tighten diesel NOx emissions. This led to many manufacturers fitting NOx traps, or NOx catalysts (SCR, or Selective Catalytic Reduction), the former of which requires a Urea-based emissions fluid (sold under the trade name, AdBlue). Intererstingly, partculate levels remained the same for both petrol and diesel.

Euro 6 (2017):

After the emissions cheating scandal, legislators realised that the laboritory tests were not representative of real-world conditions and could be manipulated. Therefore, a stricter Worldwide harmonised Light duty Test Procedure (WLTP) was introduced along with a Real Driving Emissions (RDE) on-road test.

This took some time and the test methods evolved, so some cars may be registered as being Euro 6b, or Euro 6c

You may find cars registered before 2020 as being Euro 6d-temp compliant. This means they passed the requirements during the early implimentation stage of Euro 6d, which had slightly less strict NOx limits to help manufacturers. Later compliant cars are classed under Euro 6d.

Euro 7 (2024):

As of the time of writing (April 2024), the European Council has adopted Euro VII, after manymkponths of push back from car manufacturers, who claimed the targets were unrealistic. Slated for introduction in mid-2025, it will look at otehr emissions aside from those from the tailpipe. These include particles shed from tyres and brake friction parts. HIgh voltage cars will also not escape entirely, because the standard will also assess battery durability.

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