Decarbonising Scotland’s HGVs through retrofit and repowering

Scotland has a major opportunity to accelerate progress on decarbonising its heavy goods vehicle (HGV) fleet. Although HGVs make up less than 2% of vehicles on the road, they generate around 13% of road transport emissions, meaning targeted action in this sector can deliver disproportionate benefits.

Alongside its legally-binding net zero ambitions, Scotland is committed to the UK-wide phase out of non‑zero‑emission HGVs (by 2035 for vehicles under 26 tonnes and by 2040 for all new HGVs) creating a clear pathway for industry transition. Long‑term measures such as the rollout of zero‑emission HGVs are underway and steadily gaining traction as technology and markets evolve.

But Scotland has a valuable opportunity to pursue practical interim measures that cut tailpipe emissions from the existing HGV fleet in the near term. Retrofitting, which involves upgrading older vehicles to meet stricter emissions standards, and repowering HGVs with cleaner electric, hydrogen or biomethane engine systems could assist in meeting these goals.

Retrofitting significantly reduces local air pollutants but does not deliver meaningful carbon savings, unless dual fuel hybrid retrofitting is adopted. Repowering offers true zero-emission solutions and delivers substantial carbon reductions, directly supporting Scotland’s climate targets.

Key findings

• Rigid vehicles (about two-thirds of the fleet) and articulated vehicles in the Highlands and Islands present the strongest opportunities for intervention.
• Popular models of older, non-Euro 6 vehicles are prime candidates for retrofit and repower programmes. However, for many operators purchasing used Euro 6 compliant vehicles is a similar or lower cost option compared than retrofitting.
• Battery-electric and biomethane repowering show better payback potential and are more attractive for operators intending to retain vehicles for longer periods. The most appropriate measure is dependent on the type of haulage operation the vehicles are being used for.  
• Retrofitting could remove up to 584 tonnes of nitrogen oxide and 27 tonnes of particulate matter annually – equivalent to taking thousands of cars off the road each day – but only negligible carbon (CO₂) abatement.
• Repowering the same vehicles could eliminate 1.08 million tonnes of CO₂ annually – about 57% of current HGV emissions. This falls short of the 75% reduction target, indicating that action must eventually extend to Euro 6 vehicles.

Current policy strongly favours electrification of the HGV fleet through new zero-emission vehicles. But to meet Scotland’s ambitious emissions reduction targets, policy must support both interim and long-term solutions, address economic and operational barriers, and enable a just transition for operators across the country. Only through coordinated action and targeted investment can Scotland deliver meaningful tailpipe emissions reductions now while laying the foundation for a zero-emission HGV fleet in the future.

For further information, please read the full report.

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