Euro 6 compliance and emission standards – the 2023 guide

    Last updated: 28 September 2023.

    With at least 40,000 deaths in the UK each year directly attributed to air pollution from road traffic, emissions standards are starting to be enforced in many cities across the UK.

    You’ve likely heard of the London Ultra Low Emission Zone and Birmingham Clear Air Zone, which have been in effect for several years. There are now charging CAZ and LEZ across the UK such as Bristol; as a UK driver entering major cities at any point, having a handle on compliance with the standards in these zones is essential.

    To check your diesel vehicle is Euro 6 compliant, which is the standard set across these zones, simply enter your reg into our ULEZ checker. London’s ULEZ is based on the same emissions standards as other CAZ and LEZ across the country, and it’s vital to be prepared for any charges your vehicle might incur when you travel.

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    Fortunately, our ultimate guide to Euro 6 Emission Standards will help you make the best of the situation, whether you’re about to buy a new Euro 6 vehicle or sell a car, want to save money in the future, or planning a road trip.

    Euro 6 Emissions Standards and compliance explained:

    What are the Euro 6 Emission standards?

    Petrol and diesel combustion engines inevitably produce emissions as part of their normal operation. The Euro 6 standards were introduced within the EU to try and ensure vehicle manufacturers keep harmful emissions below specific limits.

    Euro 6 Emissions Standards want to reduce pollution
    Euro 6 Emissions Standards aim to cut traffic pollution

    Only aeroplanes and seagoing ships are exempt from testing. Everything else, from scooters to trucks, has a set of standards to meet before they can be Euro 6 compliant and sold within the EU.

    That includes both petrol and diesel cars. The rules cover nitrogen oxide (NOx), carbon monoxide (CO), hydrocarbons (THC and NMHC), and particulate matter (PM). The last of which is the soot you can see emanating from the rear of diesel vehicles.

    Limits are different for petrol and diesel engines:

    • Euro 6 Diesel Emissions Standards (grams per kilometer): 0.50 CO, 0.080 NOx, 0.005 PM
    • Euro 6 Petrol Emissions Standards (grams per kilometer): 1.0 CO, 0.060 NOx, 0.005 PM

    To confuse things more, changes have been made to the testing procedure following the diesel emissions scandal. The standard was originally applied to cars type approved in September 2014 and first registered on the road in September 2015.

    Originally the testing was purely carried out in laboratory conditions (known as WLTP), and the testing methods were updated to create a new Euro 6c designation effective from September 1st, 2017.

    A new test on public roads to simulate Real Driving Emissions (RDE) has now been introduced. But whether your car is Euro 6, Euro 6c, Euro 6d-TEMP, or Euro 6d, the emission amounts are the same. The differences are purely about testing and how much discrepancy is allowed between the lab figures and those from testing on real roads. Euro 6-TEMP allows the figures to deviate by 110%, but for full Euro 6d approval, the deviation allowed will be 43%.

    Most new cars produced since the end of 2017 are Euro 6d-TEMP compliant, and some manufacturers such as Jaguar and Mercedes already exceed the full Euro 6d regulations.

    How did the Emission Standards come into being?

    The first rules covering air pollution from motor vehicles were introduced on 20th March, 1970. The Council Directive 70/220/EEC introduced tests for carbon monoxide, and hydrocarbons.

    All of the later Euro standards are amendments that have introduced tougher limits and testing. They’re listed below, alongside the date they applied for a vehicle first registration:

    • Euro 1: January 1993
    • Euro 2: January 1997
    • Euro 3: January 2001
    • Euro 4: January 2006
    • Euro 5: January 2011
    • Euro 6: September 2015
    • Euro 6d-TEMP: September 2019
    • Euro 6d: January 2021

    The purpose of these measures was to combat the risks to human health and the environment due to vehicle pollution. For example, road transport accounted for 34% of all UK NOx emissions in 2015.

    Naturally, the effect is greater in congested urban cities. The emissions contribute to smog, acid rain, and other air pollution. Carbon monoxide also creates pollution and is a leading contributor to climate change.

    Poor air quality and pollution in congested urban areas has led to stricter standards
    Pollution in congested urban areas has led to stricter standards

    The Society of Motor Manufacturers and Traders (SMMT) claim that it would take 50 new cars today to produce the same amount of pollutant emissions as one vehicle built in the 1970s.

    An even stricter Euro 7 standard will be unveiled later in the 2020s. Partly, this will continue the progress towards lower emissions, but it will also hopefully reduce some of the confusion around the various Euro 6 testing standards and ongoing compliance.

    This is likely to appear soon, as countries including the UK plan to stop the sale of new petrol and diesel cars in the next two decades.

    How will the Euro 6 emission standards affect me?

    There are a number of ways the Euro 6 emission standards affect the typical car owner. The first is the amount you pay for car tax. Vehicle tax for cars registered on or after 1st March 2001 is based on CO2 emissions and fuel type.

    Diesel cars that meet the Real Driving Emissions 2 (RDE2) standards for full Euro 6d compliance pay substantially less in tax for the first registration year. The difference can vary from £15 up to £535, which is a significant amount.

    The other most noticeable effect is if you drive into major UK and European cities. In the UK, the city-wide London Ultra Low Emissions Zone (ULEZ) affects any pre-Euro 6 diesels and pre-Euro 4 petrol cars with a standard daily charge of £12.50. You can check your car for ULEZ compliance with the our ULEZ checker. As of 2023, there is a growing list of Clean Air Zones and Low Emission Zones across the UK that charge non-compliant private passenger cars, namely: Birmingham, Bristol, and four cities in Scotland (Aberdeen, Dundee, Edinburgh and Glasgow).

    euro 6 compliance

    Similar schemes are also in operation across most major European countries. And while some cities focus purely on Heavy Goods Vehicles (HGVs), buses, and coaches, many also include passenger cars.

    The regulations are often similar to London, but some do have more stringent rules. For example, from July 4th, 2019, cars must be at least Euro 2 to enter Paris between 8am-8pm. But the plan is to increase the minimum standard until all petrol and diesel vans will be banned from Paris in 2030.

    If you’re planning a European road trip, it’s increasingly important to check the relevant city restrictions before travelling in an older vehicle. You can look by country or city on the official EU Urban Access Regulations website.

    Diesel cars use a process called Selective Catalytic Reduction, working with AdBlue which you need to add to your vehicle, to lower the amount of oxides. This injects a solution into the exhaust gases which does need refilling every few thousand miles, although it’s relatively cheap at around £1.50 per litre for a dealer to top up your system

    Ultimately, this all factors into the used car market. If you own an older car and you live in a commuter area, some car buyers may be put off. At the moment, other cities are still considering whether to implement more low emission zones in the UK, so the effect on used prices is relatively limited.

    But if you have the option to choose a Euro 6 standard car versus a slightly older model, it may well be a better investment for the future. We’ve also written a specific guide if you’re still wondering whether to buy or sell a diesel car.

    Is my car Euro 6 compliant?

    All new cars registered from September 1st, 2015 should be Euro 6 compliant. And from September 2018, the Euro Emission Standard of your car can be found on the V5C document.

    If you don’t have a logbook that tells you the emissions rating for your car, it’s worth doing a vehicle-specific check. Not only could your car have had a delay between production and registration, but even different trim and specifications of a specific car model can vary in emissions ratings.

    The good news is that you may be pleasantly surprised. Some car manufacturers have been producing Euro 6 compliant cars since as early as 2012. With earlier cars, particularly diesels, it tends to be the environmentally-focused ranges that qualify.

    For instance BMWs with the optional ‘BluePerformance’ pack, or ‘BlueHDi’ Citroen and Peugeot cars tend to be compliant with the regulations. Other brands with a wide range of earlier Euro 6 models include Volvo, Mazda, Audi, and Mercedes.

    You can check either by contacting your manufacturer or using an online checking tool.

    Euro 6 car check?

    A number of services exist for checking the emissions rating of your car and therefore its Euro 6 compliance. At the same time, you can also find out tax information and cost.

    The Vehicle Certification Agency offer one of the services which covers all new cars currently on sale in the UK, and used cars that were first registered on or after March 1st, 2001.

    You’ll need to know the month and year in which the car was first registered.

    Then you can select the type of fuel, transmission, manufacturer, model and engine description.

    To see the actual Euro Emissions Standard, click on the Description for more details, and you’ll find all the information under ‘Further Details’.

    A variety of other services exist, including one from UK Government or our ULEZ checker.

    Euro 6 diesel cars explained

    As mentioned above, to meet the Euro 6 Emission Standards, many diesel cars use a Selective Catalytic Reduction, or AdBlue process to lower the number of oxides emitted.

    This system needs to be regularly refilled, and mileages vary between cars and owners. Many drivers will find it coincides with their annual service. But if you regularly cover long distances, it may be a more frequent occurrence.

    Diesel cars have been fitted with extra technology
    Diesel cars have been fitted with extra technology to meet Euro 6 regulations

    For example, Jaguar quote the range at one litre used for between 400-550 miles depending on your model of car and driving style. This gives you 5,000-9,400 miles between refills (again, depending on the Jaguar you own).

    When it comes to choosing to buy a diesel car, most models registered since September 2015 will be compliant.

    Manufacturers with earlier examples of Euro 6 diesel cars include:

    Euro 6 conversion – how to convert your car to meet the Euro 6 standards

    If you own an older car that isn’t Euro 6 compliant, you may be wondering if you can convert it to meet the latest standards.

    For petrol cars, this isn’t really a possibility. The range of technology involved in meeting Euro 6 emissions standards is pretty complex and integrated into the design of the car. So it wouldn’t make financial sense compared to buying a car already built with those regulations in mind.

    You could possibly switch to electric or Liquid Petroleum Gas. But LPG conversions typically cost around £2,000, and the offsets in tax costs as an alternatively-fuelled car are variable year to year.

    There are substantial savings on fuel costs, but LPG has specific rules and regulations regarding usage. Meanwhile converting a car to electric power can cost from £12,000 to £20,000 if you hire a specialist company, so it would have to be a pretty special car to justify the investment.

    Diesel vehicles can potentially be converted to meet Euro 6 emission standards. Because a large part of the process to reduce harmful gases takes place in the exhaust system, it’s a more viable option.

    Upgrading an existing car to Euro 6 is very expensive
    Converting older vehicles to Euro 6 standard only really makes sense for commercial vehicles

    But while you could potentially upgrade any diesel car, it doesn’t make sense for most motorists. It will add weight, require substantial space around the exhaust system, and the cost is likely to outweigh the benefit.

    That’s why most conversion services and products are aimed at the commercial market, particularly larger and more expensive vehicles. SCR systems range from around £1,200 to £3,000.

    In Germany, the transport ministry has released guides for getting regulatory approval on retrofitted exhaust systems, with Volkswagen and Daimler offering to cover some of the costs. But in the UK, the focus so far has been on upgrading public vehicles including buses and black cabs.

    Ultimately if you’re considering converting an older diesel to meet the Euro 6 emission standards, it’s probably worth waiting if possible. As it becomes a more common need, the process should become cheaper and easier. But at the moment, it’s hard to justify on practical and financial grounds.

    Selling your car?

    Read about everything you need to know about how to sell your car with more guides here. There’s a lot to learn as Clean Air Zones and emissions standards in the UK change in the run-up to 2035.