Glossary
B7 Diesel
Direct Answer / TL;DR
What is B7 Diesel?
B7 is the standard diesel grade sold at UK forecourts. It contains up to 7% biodiesel (FAME — fatty acid methyl esters) blended with conventional diesel. The 'B7' designation indicates the maximum biodiesel content is 7% by volume.
Why does it matter for UK drivers?
B7 diesel has been the UK standard since 2010, gradually introduced under EU renewable energy directives. The biodiesel component is typically produced from waste cooking oil, rapeseed oil, or tallow, reducing lifecycle carbon emissions versus pure mineral diesel by approximately 4–7%.
Compatibility: B7 is compatible with all modern diesel vehicles designed to operate on standard pump diesel. Older injection equipment (particularly pre-2000 vehicles) may experience issues with seals at higher biodiesel blends, but B7 is well within safe limits for all cars with valid UK type approvals.
The UK government has explored moving to B10 (10% biodiesel) to reduce carbon emissions further, but this requires broader fleet compatibility checks and has not been implemented as of 2025.
Premium diesel products (Shell V-Power Diesel, BP Ultimate Diesel) are still technically B7 or B5 but include detergent additive packages that manufacturers claim improve injector cleanliness and fuel economy. Evidence for real-world economy benefits is mixed — some diesel injectors do benefit from the cleaning action, while others show no measurable difference.
For high-mileage diesel drivers — particularly those in vans, taxis, or used for long motorway commutes — the difference between cheapest and priciest diesel at the pump can represent a meaningful annual cost. WorthThePump models diesel detour savings exactly the same way as petrol, using your vehicle's diesel MPG from the DVLA lookup.
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Further reading
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