# What is B7 diesel?

B7 is standard UK diesel — mineral diesel blended with up to 7% biodiesel. It is what every forecourt sells as "diesel", it is safe for every diesel car sold in the UK, and it currently averages 197.4p a litre, 24.1p more than unleaded petrol.

Last updated: 18 September 2026

## What B7 means

B7 = mineral diesel blended with up to 7% biodiesel (FAME).
It is the standard diesel grade at UK forecourts and is safe for every diesel car sold in the UK.
The label was introduced in 2019 under an EU-wide fuel labelling standard — the fuel itself did not change.
Also seen: B100 (pure biodiesel) and XTL (synthetic/HVO diesel). Neither is interchangeable with B7 unless the vehicle is approved for it.

## Current UK diesel price

- UK average: 197.4p a litre (1485 forecourts)
- Cheapest: 107.9p · Most expensive: 226.5p
- 55-litre tank at the average: £108.57
- Premium over unleaded petrol: 24.1p a litre

## Why diesel costs more than petrol

Fuel duty is the same per litre for both, so the difference is wholesale.
European refineries produce proportionally less diesel than the continent consumes, so the shortfall is imported at extra cost.
Diesel demand is tied to freight and agriculture, so it stays firm through winter when petrol demand softens.

## Premium diesel

Same B7 base fuel with extra detergents and sometimes a cetane improver.
For a well-maintained modern car on ordinary mileage the return on the premium is thin.
The gap between the cheapest and dearest local forecourt is almost always larger than the premium-grade uplift.

## FAQ

### What does B7 mean on a diesel pump?

B7 means the diesel contains up to 7% biodiesel (fatty acid methyl ester, or FAME) blended with mineral diesel. It is the standard diesel grade at UK forecourts and is safe for every diesel car sold in the UK.

### Is B7 the same as regular diesel?

Yes. B7 is what UK forecourts have sold as standard diesel for years — the label was added to pump nozzles in 2019 under an EU-wide fuel labelling standard, alongside E5 and E10 for petrol. Nothing about the fuel changed when the labels appeared.

### Why is diesel more expensive than petrol?

Diesel currently averages 197.4p against 173.3p for unleaded — a premium of 24.1p a litre. Diesel and petrol are refined in different proportions from the same barrel of crude, and European refineries produce less diesel than the continent consumes, so the shortfall is imported. Diesel demand is also less seasonal and more tied to freight, which keeps wholesale prices firm.

### What is the difference between B7 and premium diesel?

Premium diesel is the same base B7 fuel with a different additive package — detergents intended to keep injectors clean, and sometimes a cetane improver. It costs significantly more per litre. For a car in good condition on regular servicing, standard B7 from a busy forecourt is fine.

### Can I use B7 diesel in any diesel car?

Yes, in any diesel vehicle sold in the UK. The exceptions are a small number of older and specialist engines that require fuel with no FAME content at all, which will be stated in the handbook.


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