Euro 5 vs Euro 6 emission standards

Wondering what the differences between Euro 5 and Euro 6 emissions standards are? You’ve come to the right place

Cars have become increasingly cleaner and more efficient over the years, and one of the driving forces behind these trends has been European emission standards, or Euro standards.

Introduced in stages over the last 30 years or so, Euro standards dictate what levels of pollutants petrol and diesel cars can emit in order for them to be sold from new. Euro 1 rules were introduced in 1992, and the latest regulations, Euro 6, came into force over 2014 and 2015.

But Euro standards aren’t just for car makers any longer: Clean Air and Low Emission Zones, including London’s ULEZ, have used Euro standards to decide whether drivers should pay to enter certain areas.

With Euro 6 being a core standard used for legislating against diesel cars in these zones, knowing the difference between Euro 5 and Euro 6 is of significant importance if you live anywhere close to the multiple Clean Air Zones that have sprung up across the country in recent years. You can use our free clean air zone checker to see where the boundary of these zones are in UK cities, and whether your vehicle will face charges to enter them.

What is Euro 5?

Date of introduction for brand-new models: September 2009
Date of introduction for all new cars: January 2011
Key point: mandatory particulate filters for diesel cars

Brand-new cars launched to the market (IE ones fresh from car makers’ design studios) had to meet Euro 5 from September 2009, while all new cars sold in showrooms had to meet the rules by January 2011, regardless of when those models were launched.

The most important requirement Euro 5 regulations introduced was that all diesel cars had to have particulate filters (DPFs) to comply with the rules; DPFs trap microscopic pieces of soot in them, and diesel cars without these filters could not be launched to the market from September 2009, or sold new from January 2011.

Emission limits for Euro 5 cars are as follows:

Euro 5 emission standards for petrol cars

Levels are expressed as grams per kilometre.

Carbon monoxide: 1.0g/km
Total hydrocarbons: 0.10g/km
Non-methane hydrocarbons: 0.068g/km
Nitrogen oxides: 0.06g/km
Particulate matter: 0.005g/km

Euro 5 emission standards for diesel cars

Carbon monoxide: 0.50g/km
Hydrocarbons + nitrogen oxides: 0.23g/km
Nitrogen oxides: 0.18g/km
Particulate matter: 0.005g/km
Particulate number: 6.0×10 ^11/km

Clearly those levels are not intended for study by consumers, but they’re the exhaust limits petrol and diesel cars could emit when being tested by legislators.

What is Euro 6?

Date of introduction for brand-new models: September 2014
Date of introduction for all new cars: September 2015
Key point: mandatory AdBlue systems for diesel cars

Just as Euro 5 emission regulations were stricter than Euro 4 rules, so too were Euro 6 regs tighter than Euro 5.

The two most important thing drivers need to know about Euro 6 rules are:

Euro 6 rules made selective catalytic reduction (SCR – better known as ‘AdBlue’) mandatory for diesel cars. Adblue systems squirt tiny amounts of an ammonia-based liquid into a diesel car’s exhaust fumes, greatly reducing the amount of harmful nitrogen oxides emitted by the car.

The other key thing to know is that every emission zone in the country that targets private cars requires a diesel car to meet Euro 6 standards – else the driver be charged a daily fee, or in some cases, such as Glasgow’s low emission zone, even completely banned from driving into the zone.

It’s also worth highlighting that because Euro regulations are introduced in stages, a car’s registration date is not a hard and fast metric to determine if it will meet Euro 6 rules and can be freely driven in a Low Emission Zone.

Chances are if your car was first registered after September 2015 it’ll be fine, but quirks of the regulations mean some cars sold up to 1 September 2016 may not meet the rules – so head over to our ULEZ checker to find out if your car complies.

Euro 6 emission standards for petrol cars

As with Euro 5 rules, these are not designed to be easily digestible for the man or woman in the street, but it’s worth highlighting that particulate number refers to the size of particulate pieces and the number found in a specific volume of air, while the limits for petrol particulate matter and number was only applied for cars with direct injection.

Carbon monoxide: 1.0g/km
Total hydrocarbons: 0.10g/km
Non-methane hydrocarbons: 0.068g/km
Nitrogen oxides: 0.06g/km
Particulate matter: 0.005g/km
Particulate number: 6.0×10 ^11/km

Euro 6 emission standards for diesel cars

Carbon monoxide: 0.50g/km
Hydrocarbons + nitrogen oxides: 0.17g/km
Nitrogen oxides: 0.08g/km
Particulate matter: 0.005g/km
Particulate number: 6.0×10 ^11/km

Should I upgrade to a Euro 6 vehicle?

If you live in, or on the border of a low-emission zone, or regularly travel into one, and you have a diesel car that does not meet Euro 6 emission requirements, it’s well worth working through the sums to find out how much you are likely to pay in zone charges in a year, versus the cost of upgrading your car early.

This is likely to be especially true for people living in London and the Home Counties, as the ULEZ expansion that arrived on August 29 2023 takes in almost all of greater London, including places like Heathrow Airport.

Do bear in mind that petrol cars only need to meet Euro 4 emission standards, introduced in January 2005 for brand-new model launches, and January 2006 for all new cars, in order for low-emission and clean-air rules to not apply to them. Most of us have cars that are newer than that, so it’s mainly drivers of older diesel cars who should pay extra attention.

If you are thinking about changing your car, our sell my car service will help you get a great price as our trusted dealers will bid with their best offers on it, while you can also check out our great selection of used cars, or configure a brand-new car with us.

What’s next for Euro emission standards?

It stands to reason that you may be wondering what comes after Euro 6 regulations and, if you guessed Euro 7, you’d be correct.

Euro 7 regs are due to be introduced in July 2025; the rules will set limits on the pollutants tyres and brakes can emit (these shed microscopic particles as they wear), while the longevity of electric-car battery packs will also come under scrutiny. We’ve put an in-depth guide on Euro 7 emissions together if you’d like to know more.