Supermarket forecourts are consistently the cheapest place to buy fuel in Britain — typically 3–8p per litre below branded stations in the same town, a gap our data confirms daily. Which raises the question drivers have argued about for decades: is cheap supermarket fuel somehow worse?
The short answer: it’s the same base fuel
All petrol and diesel sold in the UK must meet the same British and European standards (BS EN 228 for petrol, BS EN 590 for diesel). More to the point, supermarkets and brands very often draw from the same regional storage terminals, filled from the same refineries. The tanker that supplies a supermarket on Monday may supply a branded station on Tuesday. Fuel that fails the standard cannot legally be sold by anyone.
Where the difference is real — and how much it matters
The genuine difference is the additive package mixed in at the terminal: detergents and friction modifiers that brands formulate themselves (and advertise heavily), while supermarkets use standard packages. Additives are real chemistry — they can help keep injectors clean over tens of thousands of miles. But the effect for a typical modern car in normal use is modest, and no mainstream evidence supports the idea that supermarket fuel damages engines. The myth largely survives on anecdote.
Why supermarkets are cheaper
- Fuel is a footfall product — priced keenly to bring you to the store, not to make margin on its own.
- Volume and logistics — a busy supermarket forecourt sells multiples of a rural independent, at lower unit cost.
- No brand premium — nobody pays extra for the romance of a supermarket logo, and the pricing reflects it.
The sensible strategy
Buy supermarket fuel with a clear conscience, and if you want the additive insurance, run a tank of branded “premium” fuel occasionally — the once-in-a-while approach captures most of the claimed benefit at a fraction of the cost. And remember the gap between stations matters more than the badge on them: we mark supermarket forecourts in every search result so the discount is easy to find.