Most drivers assume supermarkets are always the cheapest place to fill up, motorway services are always a rip-off, and independents sit somewhere in the middle. The reality is more complicated than that — and getting it wrong could be costing you hundreds of pounds a year.
We track fuel prices across thousands of UK forecourts every day at Petrol Finder UK, and what the data consistently shows is that the cheapest station near you depends far more on where you live and who's competing locally than it does on whether there's a Tesco or a Shell logo on the sign.
Here's what the evidence actually tells us — drawn from the Competition and Markets Authority's own investigations, government pricing data, and what we see across our platform daily.
The Short Answer
Supermarkets are usually cheaper than other retailers — but not always, and not by as much as they used to be. Motorway services are almost always the most expensive option by a significant margin. And some independent forecourts genuinely undercut the supermarkets in their area.
The differences are not trivial. On a single 55-litre tank, the gap between the cheapest and most expensive station within a few miles of your home can easily reach £10 or more. Over a year of weekly fill-ups, that's over £500. You can see how this plays out in your area by comparing stations near you.
What the CMA Found About Supermarket Pricing
The Competition and Markets Authority has been investigating the UK fuel market in depth since 2022. Its findings make uncomfortable reading for anyone who assumes supermarkets are fighting hard to give you the lowest price.
In its 2023 road fuel market study final report, the CMA found that competition between UK fuel retailers has weakened significantly since 2019. Supermarkets had historically set the pace — pricing aggressively to draw in customers, which forced other retailers to follow. That dynamic has changed.
The CMA found that supermarket fuel margins roughly doubled between 2019 and 2023. Asda's internal fuel margin target in 2023 was more than three times what it had been in 2019, while Morrisons doubled theirs over the same period. The CMA estimated this cost supermarket fuel customers around £900 million in 2022 alone — roughly £75 million every month.
By the CMA's most recent annual monitoring report, published in December 2025, supermarket fuel margins averaged 9.6 pence per litre for the first nine months of 2025. That's down from a peak of 10.9p in 2022, but still well above the levels drivers were paying before the pandemic. For context, pre-2019 retail spreads for petrol averaged around 6.5p per litre across the industry.
So yes, supermarkets are still generally cheaper than other forecourts — but the gap has narrowed considerably, and the idea that they're selling fuel at cost to get you through the door is no longer accurate. Our prices by brand page shows how the major supermarkets and branded retailers compare right now.
How Non-Supermarket Retailers Compare
The CMA tracks non-supermarket retailers — a broad category covering branded forecourts like BP and Shell, large groups like Motor Fuel Group and EG Group, and smaller independent operators — as a separate group.
Their margins have actually been rising. For the first nine months of 2025, non-supermarket fuel margins averaged 11.1 pence per litre, up from 10.8p the previous year. Both supermarket and non-supermarket margins remain well above the historic norms the CMA uses as a benchmark for healthy competition.
But averages disguise a lot of variation. Some independents — particularly those in competitive urban areas with multiple forecourts nearby — price below the local supermarket. We see this regularly on Petrol Finder UK: a family-run forecourt undercutting the Asda or Tesco down the road because they're running a leaner operation and competing hard for every customer.
Others, particularly in rural areas or locations where they're the only option for miles, charge significantly more. The CMA's market study found that prices are likely to be higher where there are no supermarkets nearby, and that local price variation has increased as average prices have risen. Our regional price data shows where these differences are most pronounced across the UK.
The takeaway for drivers is straightforward: don't write off independents as automatically expensive, and don't assume your nearest supermarket is automatically the cheapest. Check before you fill up.
Motorway Services: The Captive Audience Premium
Motorway service stations are in a category of their own, and not in a good way.
The CMA's 2023 market study found that motorway forecourts were charging around 20 pence per litre more for petrol and 15 pence per litre more for diesel compared to other fuel stations. Since the Middle East conflict began pushing prices up sharply in late February 2026, some motorway sites have been reported charging well over 200p per litre for diesel — in some cases approaching 220p.
On a 55-litre tank, paying 20p per litre more than you needed to costs you £11 in a single fill-up. Do that on a weekly motorway commute and you're looking at over £570 a year in avoidable cost. Our commute cost calculator can show you exactly what your regular journey is costing — and what you could save.
Motorway operators have historically pointed to higher operating costs — 24-hour staffing, rent on service area land, and the infrastructure required to serve high volumes. There's some truth to this, but the CMA noted that the price premium at motorway service stations has grown in real terms since 2012, and that price variation between motorway sites is low, suggesting limited competition between them.
The practical advice here is simple and well-established: fill up before you join the motorway. If you're planning a long journey, checking prices on your route before you leave takes seconds and can save you a meaningful amount.
Why Location Matters More Than Brand
One of the most important findings from the CMA's work is that local competitive dynamics drive pricing more than brand identity does.
Where a supermarket faces genuine competition from another supermarket nearby, prices tend to be lower for everyone in that area — including the independents and branded stations who have to respond. Where a retailer — any retailer — is the dominant or only option locally, prices tend to be higher regardless of whether the sign says Tesco or BP.
The CMA put it plainly: prices are likely to be higher in areas where there are no supermarkets, or where an existing supermarket faces no supermarket competitors. In those situations, the supermarket tends to set its prices by reference to a more expensive non-supermarket retailer, rather than driving prices down.
This matters practically because it means your fuel costs are partly determined by your postcode. A driver in a town with an Asda, a Morrisons, and two independents competing for the same traffic will generally pay less per litre than a driver in a town where a single Shell forecourt is the only option within ten miles — even though both drivers are buying the same fuel. Our price heatmap gives you a visual picture of where fuel is cheapest and most expensive across the country.
What the Fuel Finder Scheme Changes
Since February 2026, every fuel retailer in the UK has been legally required to report their prices within 30 minutes of any change, under the government's Fuel Finder scheme. This data is made openly available to third-party comparison tools and apps — including Petrol Finder UK.
This is a significant change. Before the scheme launched, price data was patchy and often outdated. Drivers were making decisions based on incomplete information, which benefited retailers who could charge more without being easily compared.
The CMA, which enforces compliance with the scheme, estimated that drivers who compare prices effectively could save up to £4.50 per tank within a five-minute drive. Over a year, that adds up quickly.
The scheme doesn't directly control prices — no one is telling retailers what to charge. But by making pricing transparent and comparable in near-real time, it creates competitive pressure that benefits drivers, particularly in areas where there are genuine alternatives within a short detour. You can track how prices are moving nationally on our Fuel Watch page and see longer-term movements on our price trends page.
The Bottom Line
There is no single answer to which type of forecourt is cheapest. What the data shows is this:
Supermarkets are still the cheapest option in most areas, but their margin advantage over other retailers has shrunk significantly since 2019. The CMA's evidence shows they're no longer pricing as aggressively as they once did.
Independent forecourts vary enormously. Some are genuinely competitive — in certain locations, the cheapest station we track is an independent. Others, particularly in areas with limited competition, charge well above the national average.
Motorway service stations are consistently the most expensive by a wide margin. The premium has grown over the past decade, and with current prices elevated by the Middle East crisis, filling up on the motorway can easily cost you £10 or more per tank compared to a local station.
The single most effective thing any driver can do is check prices before filling up. The data is now there — live, accurate, and covering virtually every forecourt in the country. Using it takes a few seconds and the savings are real.
Sources:
- Competition and Markets Authority, Road Fuel Market Study: Final Report, July 2023
- Competition and Markets Authority, Road Fuel Monitoring Annual Report 2025, December 2025
- House of Commons Library, Petrol and Diesel Prices, April 2026
- Fuels Industry UK, Fuel Finder Scheme: Essential Information
