Written questions by Hayes.

What assessment her Department has made of the potential health and social impacts of illegal vehicle emissions on communities living in areas that already breach air-quality standards; and how those findings inform the Government’s net-zero and energy-efficiency policies.

Defeat devices are illegal, misleading for drivers and can have negative health impacts on the public. The Department for Transport has not conducted a specific assessment of the potential health and social impacts of illegal vehicle emissions on communities living in areas that already breach air-quality standards. Local authorities are best placed to determine the most effective route to reducing nitrogen dioxide in their cities, and we continue to support them in meeting legally binding obligations to improve air quality. This includes implementing seven Clean Air Zones and other measures such as improved traffic management, cycle lanes and funding for vehicle upgrades. Evidence shows that Clean Air Zones are effective in reducing air pollution. The government is committed to reducing emissions from diesel cars by reinstating the 2030 phase-out date for new cars relying solely on internal combustion engines, and by committing to phase out all new non-zero emission cars and vans by 2035.

What steps her Department is taking to ensure that emissions from non-compliant diesel vehicles are fully accounted for in the modelling and monitoring underpinning the UK’s Net Zero Strategy.

Emissions projections for diesel vehicles used in the recently published Carbon Budget and Growth Delivery Plan account for the difference between reported vehicle CO2 emissions, tested using the World Light Duty Test Procedure, and emissions from vehicles operating in ‘real-world’ driving conditions. The Department for Transport regularly reports its latest modelling and emissions projections to the Secretary of State for Energy Security and Net Zero as required by Section 13 of the Climate Change Act 2008.

What estimate her Department has made of the potential impact of non-compliant diesel vehicles on the UK’s ability to meet its legally binding carbon budgets and net-zero targets.

Emissions projections for diesel vehicles used in carbon budgets modelling account for the difference between reported vehicle CO2 emissions, tested currently using the World Light Duty Test Procedure, and emissions from vehicles operating in ‘real-world’ driving conditions. The Department for Transport, through the Driver and Vehicle Standards Agency, is leading investigations into suspected non-compliant diesel vehicles under assimilated Regulation (EU) 2018/858. Where non-compliance is identified, manufacturers are required to take corrective action.

Whether her Department is taking steps with the Department for Transport to improve emissions monitoring and enforcement mechanisms to prevent future breaches of vehicle emissions law.

Since 2016, the Department has greatly increased oversight of emissions tests and established the Driver and Vehicle Standards Agency’s (DVSA’s) Market Surveillance Unit (MSU) to test vehicle emissions and investigate suspicious practice in the real world as well as in laboratory situations. MSU conducts an annual emissions-testing programme and, where non-compliance is identified, the DVSA works closely with manufacturers to ensure vehicles meet legal requirements. Legislation introduced in 2018 made it an offence for manufacturers to place vehicles on the market containing prohibited defeat devices. The Department is currently assessing Euro 5 and Euro 6 diesel vehicles to identify any non-compliance and ensure corrective action is taken promptly. Enforcement action will be taken in line with DVSA’s published enforcement policy. The Department is also considering how to strengthen ways in which it can take action in situations where modifications to vehicle emissions systems result in breaches of vehicle emissions law.

What assessment her Department has made of the contribution of illegally high vehicle emissions arising from the use of defeat devices to overall UK nitrogen oxide and greenhouse gas emissions levels.

Defeat devices are illegal, misleading for drivers and can have negative health impacts on the public. The Department for Transport has not conducted a specific assessment of the contribution of illegally high vehicle emissions arising from the use of defeat devices to overall UK Nitrogen Oxide and greenhouse gas emissions levels. The Department for Transport, through the Driver and Vehicle Standards Agency, is leading investigations into suspected non-compliant diesel vehicles under assimilated Regulation (EU) 2018/858. Where non-compliance is identified, manufacturers are required to take corrective action.

What steps she is taking to investigate the use of defeat devices in diesel vehicles.

The Driver and Vehicle Standards Agency’s Market Surveillance Unit (MSU) is investigating cases of possible non-compliant diesel emissions in cars and vans. The investigations aim to ensure any non-compliance found is fixed as soon as reasonably possible, working together with manufacturers to achieve real-world impacts on air quality.Where an investigation into the emissions has identified emissions that do not meet the required standard, the MSU will work with the manufacturer to implement improvement plans and, where necessary, recall affected vehicles.

If she will take steps to ensure the recall of diesel vehicles found to use defeat devices.

The Driver and Vehicle Standards Agency’s Market Surveillance Unit (MSU) is investigating cases of possible non-compliant diesel emissions in cars and vans. The investigations aim to ensure any non-compliance found is fixed as soon as reasonably possible, working together with manufacturers to achieve real-world impacts on air quality. Where an investigation into the emissions has identified emissions that do not meet the required standard, the MSU will work with the manufacturer to implement improvement plans and, where necessary, recall affected vehicles.

What steps her Department is taking to help ensure that care leavers aged between 18 and 25 can access affordable public transport; and if she will make an assessment of the potential merits of extending the English National Travel Concession Scheme to care leavers.

This government recognises the importance of supporting care leavers, and is keeping public transport affordable having announced a new £3 cap on single bus fares in England outside London throughout the entirety of 2025.Any change to the English National Concessionary Travel Scheme (ENCTS) would require careful consideration for its impact on the scheme’s financial sustainability. However, local authorities in England have implemented a wide range of their own local fares initiatives, including some discount schemes for care leavers, utilising alternative funding, such as Bus Service Improvement Plan (BSIP) funding. On 17 November, the government confirmed £712 million funding for local authorities in 2025/26 to deliver their BSIPs and protect services, as part of an over £1 billion investment in buses confirmed at the Budget.