Open consultation

Regulating environmental impact of in-use emissions of road vehicles

Published 6 July 2026

This consultation seeks views on proposals to strengthen the law around emissions from road vehicles that are in-use in Great Britain (GB).  

The proposals aim to ensure that road vehicles continue to meet the same legal emissions requirements that applied when they were built and first registered for use on the roads.

This will:

• promote vehicle maintenance and enable stronger enforcement to improve air quality
• protect human health

Introduction

Government is committed to cleaning up our air and protecting the public from the harms of pollution. Poor air quality disproportionately affects low-income communities, deepening existing health and social inequalities.

It has been linked to some of the most severe and costly challenges facing the NHS, including heart disease and strokes. Vulnerable groups such as older adults, young children, those with respiratory conditions and pregnant women are particularly at risk.

Road vehicle emissions pose a serious threat to the environment and public health. Road vehicles are the single largest source of nitrogen oxides, which have a significant negative impact on air quality and consequently human health.

As well as the effects of nitrogen oxides, road vehicles are the second largest source of atmospheric fine and ultrafine particulates, the inhalation of which has also been linked to severe health conditions and has been increasingly recognised as a significant contributor to poor air quality^{[footnote 1]}.

In the UK, to protect the environment and public health, emissions from road vehicles are regulated before vehicles are sold or registered. This is achieved by manufacturers demonstrating that they comply with legally binding technical standards.

However, once vehicles are on the road, there are limited legal tools to ensure that vehicle emissions control systems (ECS) remain functioning as intended at the time they were built and registered, meaning that emissions of pollutants from a vehicle in-use may be higher than when the vehicle was new. Evidence indicates that stronger legal measures are needed to make sure emissions remain properly controlled throughout the life of road vehicles. 

Our proposal aims to bring in stronger measures to ensure emissions are properly controlled throughout a vehicle’s life, because poorly maintained or modified ECSs can lead to increased nitrogen oxides and particulate emissions, negatively affecting air quality and public health.

Overview of current regulation of emissions

Great Britain has a range of stringent and legally binding environmental and safety standards for vehicles, which protect the public from harm.

Broadly, the regulatory framework operates as follows: 

• Manufacturers must demonstrate that newly built vehicles and their parts meet the legal standards. The vehicles must be approved by a designated authority before being placed on the market. 

• Once vehicles are in-use, the rules in the Road Vehicles (Construction and Use) Regulations 1986 (the 1986 regulations) apply. These rules contain requirements for vehicles to be maintained to the same standards as those at approval. Similar but separate legislation and policy apply in Northern Ireland to regulate vehicles in-use.

Emissions standards are regulated in accordance with this broad framework and manufacturers must also demonstrate that their emissions technology performs as expected for 100,000 km or 5 years, whichever occurs sooner. This applies to properly maintained and used vehicles. A durability requirement also applies to separate pollution control devices, such as catalytic converters, which must last for 160,000 km.

The emissions standards that apply when the vehicle is built and registered are known as the ‘Euro standards’. These set the maximum tailpipe emission limits and any other requirements of the ECS, such as dashboard warning lights. 

Euro standards are designed to protect the environment (air quality) and thus public health: they were first introduced in 1992 and have evolved since then, getting stricter.

Each version of the Euro standards is numbered as follows:

• for light-duty vehicles, Euro 1, Euro 2 up to current Euro 6 
• for heavy-duty vehicles, Euro I, Euro II, up to current Euro VI

The Euro standards remained part of domestic law after the UK left the European Union, so all vehicles being manufactured for use on GB roads must continue to meet the most up-to-date emissions standards.

The rules about emissions from vehicles in-use in GB (regulation 61A) were added to the 1986 regulations in 2000 and regulate in-use emissions for certain types of vehicles first used on or after 1 January 2001. 

Regulation 61A applies to all light-duty, passenger and goods vehicles, such as cars, vans, lorries and trucks, buses and coaches (all category M and N vehicles).

At the time it was introduced, regulation 61A required that vehicles in-use had to continue to meet the limits and requirements set out in the Euro standard at the time of build and registration. This ensured that the integrity and purpose of the new-build emissions standards were not undermined by poor maintenance or modifications to the emissions system once the vehicle was on the road.

The law initially stated that no person could use, cause or permit to be used a motor vehicle on the road if it did not comply with its legal build standard through cross-references to that legislation. Any breach of this might mean that an offence was committed.

At the time that this law took effect, the applicable standards were:

• Euro 3 for cars
• Euro 2 for vans
• Euro II for lorries and buses/coaches

The law was amended several times to account for improvements and amendments to the Euro standards, which covered up to Euro 4 and Euro V.

However, no further amendments were made to the 1986 regulations to reflect newer, more stringent Euro standards. This leaves the situation where most vehicles on the road are not regulated in a manner that ensures ongoing compliance with emissions build standard.

Why we are reviewing the law

There is now a gap in the emissions laws between what is required when a vehicle is newly built and registered and when it is in use on the roads. There is no requirement to maintain the functioning of the ECS of Euro 5 or 6 light-duty vehicles or Euro VI heavy-duty vehicles. 

In our view, this gap has contributed to vehicles being poorly maintained or modified in ways that increase emissions, which has led to poorer air quality and negative impacts on public health. It has also left a law where the burden of maintenance falls to those with older vehicles.

We have reviewed available sources of data on emissions from vehicles currently in-use. These support the view that there is a negative environmental impact on air quality caused by vehicle emissions that are higher than the legal limits set at the time of the vehicles’ build.

Feedback we have received indicates that many vehicles in the UK emit pollutants above the build limits. A recent study using roadside remote-sensing technology looked at over 94,000 vehicles across several UK cities and found that fewer than 1 in 10 passenger cars met the official limits for nitrogen oxides.

Around two‑thirds of Euro 5 and Euro 6 diesel cars were emitting more than 3 times the level allowed. Data also shows that a relatively small proportion of high-emitting vehicles can account for a disproportionate share of total emissions^{[footnote 2]}. These high emissions are often associated with faulty, degraded or modified ECS.

Transport remains the UK’s largest source of nitrogen oxides and a major contributor to particulate matter (PM). While nitrogen oxides emissions fell by 44% between 2010 and 2020 due to tighter standards and fleet renewal ^{[footnote 3]}, excess emissions linked to failed, modified or degraded ECS continue to erode these gains, particularly in urban areas where exposure is highest ^{[footnote 4]}.

These emissions also impose significant health and economic costs. The UK Health Security Agency estimates that around £9.4 billion in NHS and social care costs are attributable to PM^{[footnote 1][footnote 4]} and £9.2 billion from nitrogen dioxide between 2017 and 2035. Achieving the World Health Organization PM^{[footnote 1][footnote 4]} guideline (10 µg/m³) could provide approximately 40,000 additional productive life years, valued at around £1 billion^{[footnote 2][footnote 5]}.

So, although existing rules ensure that new vehicles meet strict emissions standards, this evidence shows that stronger measures are needed to make sure emissions remain properly controlled throughout a vehicle’s life.

The 2035 phase-out of all new non-zero emission cars and vans will not eliminate the problem of excess emissions from vehicles already on the road. Even with the rapid uptake of zero emission vehicles (ZEVs), large numbers of internal combustion engine (ICE) vehicles will remain in use for many years. This highlights the need for continued government action, as the 2030 and 2035 phase‑outs alone will not resolve in‑use emissions from the existing fleet.

Government research from 2025 shows that petrol and diesel cars will remain common on UK roads for many years, with 37% of people expecting their next car to be petrol and 13% expect to buy diesel, while 13% of people intend to buy a fully electric vehicle.

Additionally, the survey also shows that most people (72%) expect their next car to be second‑hand, especially those on lower incomes or those who do not currently own a vehicle. Because the second‑hand market still consists mainly of older petrol and diesel vehicles, this suggests that cars with tailpipe emissions will stay on the road for a long time.

Looking more anecdotally at modifications being made to the ECS of vehicles, search engine history suggests that there are many businesses offering vehicle modifications with names such as ‘DPF delete’ or ‘AdBlue delete’. These sorts of changes mean that vehicles will emit pollutants well in excess of the limits set for new vehicles.

The market surveillance unit (MSU), based within the Driver and Vehicle Standards Agency (DVSA), receives intelligence and reports associated with activity that would be considered modification of emissions systems. In 2024, MSU received 331 intelligence reports associated with emissions modifications. We suspect that such reports are likely to be only a small proportion of the activity.

Our proposal

To control excess emissions from in-use vehicles, we propose to make it a legal requirement that all road vehicles in-use in GB must have their ECS maintained in such a way that the maximum level of emissions and other requirements of the control system continue to operate as set by law at the time of manufacture.

We intend to update regulation 61A to make use of existing sections of the Road Traffic Act 1988: 

• section 42: use of a vehicle that does not comply with construction and use requirements
• section 75: alterations to vehicles
• section 76: fitting or supply of unsuitable vehicle parts

Depending on the circumstances, breaches of these sections can result in fines of between £1000 and an unlimited amount following successful prosecution in the magistrates’ court. 

This means that the following will be prohibited:

• using a vehicle on the road which has been maintained or modified in a way that means it no longer meets the emissions standards that it was approved to 

• allowing a vehicle to be used on the road which has been maintained or modified in a way that means it no longer meets the emissions standards that it was approved to 

• modifying a vehicle yourself, or allowing a vehicle to be modified, in a way that means it no longer meets the emissions standards that it was approved to

We have chosen not to distinguish between excess emissions caused by poor maintenance of a vehicle and those caused by modifications made to vehicles.

Similarly, we do not propose to distinguish unintentional and deliberate modifications made to the ECS, nor whether these are through hardware or software alterations. The environmental and health impacts of excess emissions are the same, regardless of the reason. Such distinctions can also be difficult to evidence and would make enforcement unreasonably difficult. 

We also want to encourage good vehicle maintenance, which may avoid more expensive repairs following catastrophic failure.

Exempted situations

However, we also recognise that, even where emissions exceed the relevant limits, there will be situations where exemptions arise and no offence is committed. Such exempted situations exist in the current regulation 61A. We want to ensure that in any updated law, we have properly considered when a person would not be at fault.

Currently, regulation 61A exempts the vehicles from compliance with the emissions limits in the following situations: 

• where the vehicle is used off-road

• the reason for the vehicle having excess emissions is something outside the control of the owner/ user, where: the cause is not a modification made once the vehicle is in-use, normal servicing would not fix the problem and all emission‑control devices (such as a DPF) are present and working correctly

• the vehicle is being driven to have an emission‑control device fixed/repaired, the cause of the excess emission is not modification and normal servicing would not fix the problem

• the vehicle is being driven to a port for export

• the user of a vehicle is a vehicle examiner, such as an MOT tester, during/after the vehicle’s test

• the vehicle has been brought into GB for no longer than 6 months by a person who lives abroad and complies with certain basic safety and equipment rules

Regulation 61A questions

Question: Do you agree or disagree with amending existing law so that all road vehicles should maintain the same emissions standards throughout life, as applied when they were built and first registered?

Question: If you disagree, why do you think this?

Question: Do you agree or disagree that poor maintenance should be regulated? Explain why you think this.

Question: Do you agree or disagree that vehicle modification should be regulated? Explain why you think this.

Which of the following exempted situations do you think we should include in updated legislation? 

• faults that are outside the control of the owner and user in defined circumstances
• vehicles brought into GB temporarily by a person who lives abroad (up to a total of 6 months in 12 months)
• vehicles that are being driven to have an emission-control device fixed 
• vehicles that are being driven to a port for export 
• vehicle used off-road 
• other circumstances

Note: let us know what other circumstances there may be where we should consider that no offence has been committed.

Vehicle modifications

We are not seeking to prohibit all vehicle modifications. Our view is that vehicle alteration is a legitimate practice that has been embraced by car tuners, repairers and enthusiasts worldwide.

Additionally, we are not seeking to stop owners or businesses from installing parts that are generic rather than manufacturer-specific original equipment manufacturer (OEM), although we would advise that anyone installing parts to vehicles does check that they are legally approved for use. It is already illegal to fit or supply unsuitable or illegal vehicle parts and can be punished in the courts with an unlimited fine.

The legality of a vehicle modification, whether to hardware or through alteration to software, depends primarily on how that modification affects the standard to which it was legally built. 

Some modifications that are made to the emissions control system of a vehicle can worsen the emissions to the point where it no longer meets the legal new-build limits. This effect upon emissions does not have to be intended and could be because of an alteration being performed for other reasons.

Some modifications of emissions systems can be associated with other modifications considered unlawful, such as those made to achieve exhaust noise above legal limits, often referred to as ‘pop and bang’.

Modifications that we would always consider illegal, because of their known and proven effect upon legal limits of emissions, would include: 

• removal or ‘deletion’ of diesel particulate filters (DPF) in diesel vehicles or gasoline particulate filters (GPF) in petrol vehicles

• removal of 3-way catalysts (TWC), commonly known as catalytic converters, often accompanied by alteration or removal of sensors and sometimes engine control unit (ECU) remapping

• manipulation of the selective catalyst reduction (SCR) systems and diesel exhaust fluid (DEF) in diesel vehicles through a process often referred to as ‘AdBlue Delete’

• manipulation of the exhaust gas recirculation (EGR) system in diesel vehicles, whether physical (such as obstructing the gas tubing or disconnecting the valves and rewiring to a device which mimics their operation) or remapping the ECU

Vehicle modification question

Question: Do you agree or disagree that, where it is a known and proven fact that a particular modification will always result in illegal levels of emissions, this modification should be considered unlawful? Explain why you think this.

Other categories of vehicle

Regulation 61A has never applied to any category L vehicle (mopeds, scooters, motorcycles, tricycles and quadricycles). However, these have their own Euro standards that apply at the time of build and registration for use on the road and there are other construction and use rules that apply to the maintenance and alteration of motorcycle exhaust systems.

We have limited analytical evidence specific to in-use emissions from motorcycles. However, given that they have the potential to contribute to excess emissions when in-use we have not identified any clear policy or technical reasons to exclude them from the scope of the updated regulation. Therefore, we propose that an updated regulation 61A should apply to these vehicle categories.

Other categories of vehicle question

Question: Which of the following types of vehicles do you think an updated law controlling in-use emissions should apply to? Explain why you think this.

• large and heavy passenger vehicles (category M3) – buses and coaches
• large and heavy goods vehicles (category N3) – lorries
• medium goods vehicles (category N2) – vans
• medium passenger vehicles (category M2) – minibuses
• small passenger vehicles (category M1) – cars and small vans
• small goods vehicles (category N1) – vans
• 2-or 3-wheel vehicles and quadricycles (category L) – mopeds, scooters, motorcycles, tricycles, and quadricycles

Proposed timelines for implementation

We envisage that new legislation will be passed in the summer of 2027.

We intend to allow a lead-in time before the law is active so that owners can have any relevant servicing done and businesses can make any necessary adjustments to their activities and advertising.

We propose a lead-in time of 6 months.

Proposed timelines for implementation questions

Question: Do you agree or disagree that there should be a 6-month period of adjustment?

• agree with 6 months
• disagree with 6 months, the law should take effect as soon as it is passed
• disagree with 6 months, the lead-in time should be less than that
• disagree with 6 months, the lead-in time should be more than that

Question: What is your chosen period and why?

Once the law is active, we can properly enforce, taking appropriate and proportionate action against those who do not comply. All enforcement is expected to be carried out by DVSA. 

Some aspects of emissions can be assessed during annual roadworthiness checks, but the scope of what can be assessed is limited.

Therefore, our focus will likely be upstream and focus on addressing practices that involve illegal modifications to the ECS of vehicles.

How to respond

We will only accept responses received before the closing date: 11:59pm on 6 September 2026.

The easiest way to respond is to use the online response form. It includes the option to save and continue your response if you are unable to complete it in one go.

If you cannot use the online form, email or post your response to us:

Email to: ivs.consult@dft.gov.uk

Write to:

International vehicle standards team
Department for Transport
Great Minster House
33 Horseferry Road
London, SW1P 4DR

If you send your response by email or post:

• answer the questions asked in the consultation and, if required, provide further comments and evidence
• tell us if you are responding as an individual or on behalf of an organisation

If responding on behalf of an organisation, you need to:

• make it clear who the organisation represents
• outline how the views of members were assembled (where applicable)

You will receive an acknowledgement of receipt if you submit your response by email. Check your junk/spam folder if you do not receive this within 15 minutes of sending your email. If you do not find a receipt, email ivs.consult@dft.gov.uk with ‘missing receipt’ in the subject line.

What happens next

We will publish a summary of responses and the government response on the homepage for this consultation. Paper copies will be available on request.

Full list of questions

This list of questions provides an overview of what we are asking.

About you

Question: What is your name?

Question: What is your email address?

Question: Are you responding on behalf of an organisation?

Question: What is the name of your organisation?

Question: What best describes your organisation?

• academic
• business – aftermarket parts manufacturer
• business – aftermarket parts supplier
• business – vehicle repair and maintenance that also conducts MOT testing
• business – vehicle repair and maintenance that does not conduct MOT testing
• business – vehicle remapping, tuning and modification
• consumer focused organisation
• environment interest groups
• government
• health interest groups
• legal
• trade association
• vehicle fleet owner or operator
• vehicle manufacturer
• other organisation

Question: How many people does your response represent?

Question: Do you currently own at least one motor vehicle?

Question: If yes, what type of motor vehicle do you own?

• bus
• car
• lorry
• motorbike
• moped
• van
• other type of motor vehicle

Question: Do you regularly use at least one motor vehicle that is owned by someone else?

Question: If yes, what type of motor vehicle do you regularly use?

• bus
• car
• lorry
• motorbike
• moped
• van
• other type of motor vehicle

Proposal

Question: Do you agree or disagree with amending existing law so that all road vehicles should maintain the same emissions standards throughout life, as applied when they were built and first registered?

Question: If you disagree, why do you think this?

Question: Do you agree or disagree that poor maintenance should be regulated? Explain why you think this.

Question: Do you agree or disagree that vehicle modification should be regulated? Explain why you think this.

Question: Which of the following exempted situations do you think we should include in updated legislation? 

• faults that are outside the control of the owner and user in defined circumstances
• vehicles brought into GB temporarily by a person who lives abroad (up to a total of 6 months in 12 months)
• vehicles that are being driven to have an emission-control device fixed 
• vehicles that are being driven to a port for export 
• vehicle used off-road 
• other circumstances

Vehicle modification

Question: Do you agree or disagree that, where it is a known and proven fact that a particular modification will always result in illegal levels of emissions, this modification should be considered unlawful? Explain why you think this.

Other categories of vehicle

Question: Which of the following types of vehicles do you think an updated law controlling in-use emissions should apply to? Explain why you think this.

• large and heavy passenger vehicles (category M3) – buses and coaches
• large and heavy goods vehicles (category N3) – lorries
• medium goods vehicles (category N2) – vans
• medium passenger vehicles (category M2) – minibuses
• small passenger vehicles (category M1) – cars and small vans
• small goods vehicles (category N1) – vans
• 2-or 3-wheel vehicles and quadricycles (category L) – mopeds, scooters, motorcycles, tricycles, and quadricycles

Proposed timelines for implementation

Question: Do you agree or disagree that there should be a 6-month period of adjustment?

• agree with 6 months
• disagree with 6 months, the law should take effect as soon as it is passed
• disagree with 6 months, the lead-in time should be less than that
• disagree with 6 months, the lead-in time should be more than that

Question: What is your chosen period and why?

Final comments

Question: Do you have any other comments?

The easiest way to submit your answers is to use the online response form. For other ways to submit your answers, see how to respond.

Further information

Freedom of information

Information provided in response to this consultation, including personal information, may be subject to publication or disclosure in accordance with the Freedom of Information Act 2000 (FOIA) or the Environmental Information Regulations 2004.

If you want information that you provide to be treated as confidential, please be aware that, under the FOIA, there is a statutory code of practice with which public authorities must comply and which deals, amongst other things, with obligations of confidence.

In view of this, it would be helpful if you could explain to us why you regard the information you have provided as confidential. If we receive a request for disclosure of the information, we will take full account of your explanation, but we cannot give an assurance that confidentiality can be maintained in all circumstances. An automatic confidentiality disclaimer generated by your IT system will not, of itself, be regarded as binding on the department.

Data protection

Your consultation response and the processing of personal data that it entails are necessary for the exercise of our functions as a government department. DfT will, under data protection law, be the controller for this information. 

Personal data collected through this consultation is processed in line with our online forms, surveys and consultations privacy notice. 

DfT’s privacy policy has more information about your rights in relation to your personal data, how to complain and how to contact the data protection officer.

Artificial intelligence

Artificial intelligence (AI) may be used to analyse responses to this consultation. Where the consultation asks for directly identifiable information, such as your name or contact details, these will be removed before processing with AI tools.

1. Ohlwein S, Kappeler R, Kutlar Joss M, Kunzli N, Hoffmann B. ‘Health effects of ultrafine particles: a systematic literature review update of epidemiological evidence.’ International Journal of Public Health 2019: volume 64, issue 4, pages 547 to 559. ↩ ↩² ↩³

2. Omid Ghaffarpasand, Karl Ropkins, David C.S. Beddows, Francis D. Pope, Detecting high emitting vehicle subsets using emission remote sensing systems, Science of the Total Environment, volume 858, part 2, 2023, article 159814, ISSN 0048-9697. ↩ ↩²

3. DfT air quality and transport internal evidence briefing, 2024. ↩

4. The Greater London Authority (GLA) Air pollution and inequalities in London: 2019 update (PDF). ↩ ↩² ↩³

5. The UK Health Security Agency (UKHSA) Chemical hazards and poisons report: issue 28. ↩