Motorway service station (MSA) fuel is consistently among the most expensive in the UK, often 10–20p per litre more than a supermarket forecourt a few miles away. It isn't usually because the fuel itself is any different — it's almost entirely down to the economics of operating a forecourt on motorway land.
Why MSA fuel costs more
Motorway service stations pay significantly higher rent than a typical roadside or supermarket forecourt, have no local competing stations to keep prices in check, and serve a captive audience of drivers who often can't easily leave the motorway to shop around. Fuel retailing at MSAs is also frequently run under different commercial arrangements than supermarket or independent forecourts, with less pressure to compete on price the way stations do when they're a five-minute drive from three rivals.
Practical ways to pay less
The simplest fix is timing your fuel stop for just before or just after the motorway section of your journey rather than at the services themselves — supermarket forecourts (particularly ones attached to large stores) are consistently among the cheapest nationally, and are often only a few minutes off your route at a junction. Searching by postcode on the Local Petrol Prices homepage before a long journey, or checking the relevant county page for somewhere near your route, can show you exactly which nearby stations are cheapest before you set off, rather than relying on guesswork or whichever sign you happen to pass.
Planning ahead for long trips
For longer journeys, it's often worth filling up fully before joining the motorway rather than topping up partway through, since every motorway stop is a chance to pay the MSA premium on fuel you didn't strictly need yet. If you do need to stop at services for a break, you can still choose not to fill up there — a short detour to a nearby town on the way back onto the motorway is frequently enough to find noticeably cheaper fuel for the same round trip.