Members-only forecourts at warehouse clubs, routinely among the cheapest prices in the country.
Daily network average, petrol and diesel
Costco sells fuel only to members, at a small number of forecourts attached to its warehouses. The prices are consistently among the lowest in Britain — often several pence below the nearest supermarket — because the fuel is a membership benefit rather than a profit centre.
The catch is arithmetic. Membership costs a fixed annual fee, so the saving only turns positive above a certain annual mileage, and only if a Costco is on a route you already drive. For a driver filling a 55-litre tank fortnightly at a five-pence saving, the fuel alone roughly covers a standard membership; below that, it does not.
There are few enough Costco forecourts that for most of the country the question does not arise. Where one is nearby, it is usually the cheapest option on the map.
Sites by UK region, with the local median price
Coverage explains a good deal of what looks like brand pricing. Fuel is cheaper in some regions than others whatever the sign says, so a chain weighted towards the cheaper ones shows a lower national average without any of its sites pricing unusually.
Costco is averaging £1.62 a litre for E10 petrol across 22 UK forecourts — £89.05 for a 55-litre tank. The cheapest Costco forecourt in the country is currently £1.55.
Costco is 8.0p below the UK median of £1.70, which places it 1st of 29 ranked brands. Routinely the cheapest fuel in its area, but only to members and only at a handful of locations.
22 Costco forecourts are in our data, all currently quoting a price, spread across 9 of the twelve UK regions.
Yes — Membership required to buy fuel. Loyalty shifts the effective price by an amount that depends on how much you redeem rather than how much you fill, so it is worth counting only if you actually use it.
Costco sites generally sell standard E10 petrol and B7 diesel, though some also stock super unleaded, averaging £1.72.
Search your postcode on FuelSignal and filter by brand. Prices come from the government Fuel Finder feed, which has required every UK forecourt to report a change within thirty minutes since February 2026, so what you see is what is on the sign.
1st cheapest of 29 ranked brands
Price, network size and coverage, side by side
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