Euro emissions standards

The first European exhaust emissions standard for passenger cars was introduced in 1970.

22 years passed before the next big change when, in 1992 the 'Euro 1' standard heralded the fitting of catalytic converters to petrol cars to reduce carbon monoxide (CO) emissions.

The latest standard, 'Euro 6', applies to new type approvals from September 2014 and all new cars from September 2015 and reduces some pollutants by 96% compared to the 1992 limits.

The Euro 6 test became more stringent from September 2017 with the addition of an extended on-road emission test known as Real Driving Emissions or RDE.

The dates below are the implementation date for new vehicle type approvals. The dates in brackets are the implementation date for all new vehicle registrations, normally one year later, so a car registered between the two dates may meet the corresponding emissions standard and a car registered after the date in brackets will meet it.

CO = Carbon Monoxide

NOx = Oxides of Nitrogen

HC = Hydrocarbons

PM = Particulate matter

Euro 1 (EC93)

July 1992 (January 1993)

The introduction of the Euro 1 standard in 1992 required the switch to unleaded petrol and the universal fitting of catalytic converters to petrol cars to reduce carbon monoxide (CO) emissions.

Euro 2 (EC96)

January 1996 (January 1997)

The Euro 2 standard further reduced the limit for carbon monoxide emissions and also reduced the combined limit for unburned hydrocarbons and oxides of nitrogen for both petrol and diesel vehicles. 

Euro 2 introduced different emissions limits for petrol and diesel.

Euro 3 (EC2000)

January 2000 (January 2001)

Euro 3 modified the test procedure to eliminate the engine warm-up period and further reduced permitted carbon monoxide and diesel particulate limits. Euro 3 also added a separate NOx limit for diesel engines and introduced separate HC and NOx limits for petrol engines.

Euro 4 (EC2005)

January 2005 (January 2006)

Euro 4 (January 2005) and the later Euro 5 (September 2009) concentrated on cleaning up emissions from diesel cars, especially reducing particulate matter(PM) and oxides of nitrogen (NOx).

Some Euro 4 diesel cars were fitted with particulate filters.

Euro 5

September 2009 (January 2011)

Euro 5 further tightened the limits on particulate emissions from diesel engines and all diesel cars needed particulate filters to meet the new requirements. There was some tightening of NOx limits too (28% reduction compared to Euro 4) as well as, for the first time, a particulates limit for petrol engines – applicable to direct injection engines only.

Addressing the effects of very fine particle emissions, Euro 5 introduced a limit on particle numbers for diesel engines in addition to the particle weight limit. This applied to new type approvals from September 2011 and to all new diesel cars from January 2013.

Euro 6

September 2014 (September 2015)

The Euro 6 standard imposes a further, significant reduction in NOx emissions from diesel engines (a 67% reduction compared to Euro 5) and establishes similar standards for petrol and diesel.

Exhaust Gas Recirculation (EGR) – replacing some of the intake air (containing 80% nitrogen) with recycled exhaust gas – reduces the amount of nitrogen available to be oxidised to NOx during combustion but further exhaust after treatment may be required in addition to the Diesel Particulate Filters required to meet Euro 5.

Euro 6 diesel cars may also be fitted with:

• A NOx adsorber (Lean NOx Trap) which stores NOx and reduces it to Nitrogen over a catalyst
• Selective Catalytic Reduction (SCR) which uses an additive (Diesel Exhaust Fluid (DEF) or AdBlue) containing urea injected into the exhaust to convert NOx into Nitrogen and water.
• The use of Cerium, a fluid injected into the fuel tank each time the vehicle is refuelled which assists the DPF regeneration by lowering the temperature needed for regeneration.

Euro 6d-Temp, Euro 6d and Real Driving Emissions (RDE)

From 1 September 2017, more stringent and realistic tests will be used to certify new car models against the Euro 6 emission limits.

A new laboratory test cycle known as WLTP (the Worldwide harmonised Light duty Test Procedure) will apply to all new type approvals and a year later, from 1 September 2018, will apply to all new car registrations.

An additional, on road, emissions test known as the Real Driving Emissions or RDE test has been introduced alongside the WLTP laboratory test to help make sure that cars meet emissions limits in a much wider range of driving conditions.

An RDE test will last between 90 and 120 minutes and take in a mix of 'normal' urban, rural and motorway driving.

RDE is being introduced in two steps:

RDE step 1 – applies to new type approvals from 1 September 2017 and to all new registrations from 1 September 2019.

• For RDE1 a NOx conformity factor of 2.1 will apply meaning that NOx emissions in the RDE1 test can be up to 2.1 times the Euro 6 laboratory limit of 80mg/km.
• Cars type approved during this period will be described as meeting Euro 6d-temp.

RDE step 2 – applies to new type approvals from 1 January 2020 and to all new registrations from 1 January 2021.

• For RDE2 the NOx conformity factor is 1.0 but with an error margin of 0.5 meaning that NOx emissions in the RDE2 test can be up to 1.5 times the Euro 6 laboratory limit of 80mg/km.
• Cars type approved during this period will be described as meeting Euro 6d.

From September 2018, the Euro standard to which a new car has been certified will be shown on the V5c vehicle registration document and the online ' Get vehicle information from DVLA ' service.

In the Autumn 2017 budget the Chancellor announced an increase in the first year VED rate of one band for new diesels first registered from 1 April 2018 that don't meet the Euro 6d standard.

Updated 11 December 2017