Supermarket fuel prices

How much cheaper supermarkets actually are

Unleaded averages 169.9p at supermarket forecourts and 173.9p everywhere else — a 4.0p gap. Diesel shows a similar pattern: 192.8p against 198.2p, a gap of 5.4p.

Put in terms that matter: a driver covering 12,000 miles a year in a car returning 40mpg burns roughly 1,360 litres. At a 4.0p gap, always using supermarket forecourts instead of branded ones is worth about £54 a year.

The caveat that matters more than the average: supermarkets price each site against its local competition, not nationally. A supermarket forecourt with no nearby rival can be dearer than a branded site in a competitive town. The town-by-town pages show what is actually cheapest where you are.

Asda vs Tesco vs Sainsbury's vs Morrisons

The order changes week to week and the differences between the four are small compared with the gap to branded forecourts. Treat the table as a guide to who is currently keenest nationally, not as a reason to drive past a cheaper rival.

Is supermarket fuel worse for your car?

This is the most persistent myth in UK motoring, and the answer is no.

All petrol sold in the UK must meet BS EN 228 and all diesel BS EN 590. Those standards govern octane and cetane rating, sulphur content, volatility, contamination limits and more. A supermarket cannot sell fuel that fails them any more than a branded retailer can. In practice supermarkets and branded retailers frequently draw from the same refineries and the same distribution terminals — the tanker filling a supermarket forecourt may well have filled a branded one on its previous run.

The real difference is the additive package blended in at the terminal. Branded premium fuels — V-Power, Ultimate, Momentum — carry heavier detergent doses than standard fuel, supermarket or otherwise. That is a genuine difference, but it is a difference between premium and standard grades, not between supermarket and branded. A standard branded unleaded and a supermarket unleaded are far closer to each other than either is to a premium grade.

For a car in good condition on a normal service schedule, supermarket fuel is fine indefinitely. If you want the detergent benefit, an occasional tank of premium achieves more than paying a permanent brand premium on standard fuel.

Why supermarket fuel is cheaper

Three reasons, in order of importance:

1. Fuel is a loss leader. Supermarkets do not need the forecourt to make money. A cheap price on a large roadside sign brings cars into the car park, and the margin is recovered inside the store. A standalone forecourt has no such second business.
2. Volume. Supermarket sites are high-throughput, selling far more litres per site than a typical independent. Fixed costs — staff, maintenance, the site itself — are spread across many more sales.
3. Buying power. The chains buy enormous volumes on terms an independent retailer cannot match.

None of those reasons involve the fuel itself being different.