Fuel is one of the largest and most volatile costs of running a car or a van in the UK. Yet most drivers still fill up at whichever forecourt is closest, glance at the headline price, and hope for the best. If you want to genuinely cut your motoring costs, you need to learn how to compare fuel properly, and that means looking well beyond the number on the big illuminated sign by the kerb.
This guide explains how to compare fuel like a data-driven professional. We will cover comparing pump prices between stations, comparing the true cost of petrol versus diesel versus electric, working out pence per mile, and the tools that make the whole job effortless. Whether you are a single driver trying to trim your monthly outgoings or a small fleet operator managing a dozen vehicles, the principles are the same.
Why Comparing Fuel Properly Matters
The gap between the cheapest and most expensive forecourts in the same town can easily be 10 to 15 pence per litre. On a typical 50-litre fill, that is £5 to £7.50 every single time you brim the tank. Multiply that across a year of weekly fill-ups and a careless driver is handing over £250 to £350 they did not need to spend. For a fleet of ten vans, the same carelessness becomes thousands of pounds annually.
The problem is that the headline pump price is only part of the story. To compare fuel fairly, you need to factor in three things: the price per litre, how far you actually have to drive to reach the cheaper station, and how efficiently your vehicle converts that fuel into miles. A station that is 4p cheaper but a 6-mile detour away may cost you more once you account for the extra fuel burned getting there.
Good comparison is about the total cost of covering a mile, not the cost of a single litre. Once you internalise that shift in thinking, every other decision becomes clearer.
How to Compare Fuel Prices Between Stations
The first and easiest win is comparing local forecourt prices before you drive. Petrol and diesel prices vary enormously depending on the retailer, the location, and local competition.
Supermarkets versus branded forecourts
As a rule of thumb, the big supermarkets (Asda, Tesco, Sainsbury's and Morrisons) tend to be among the cheapest in any given area because they use fuel as a footfall driver. Branded motorway service stations are almost always the most expensive, often 15 to 20p per litre higher than a supermarket only a few miles away. Independent rural forecourts sit somewhere in between and can be pricey where there is little competition.
Following pressure from the Competition and Markets Authority, the Government has introduced a statutory fuel price transparency scheme called Fuel Finder, which requires retailers to share live prices. You can read more about the open-data approach on the official CMA road fuel pages on gov.uk. The practical upshot for you is that accurate, near-real-time pricing is increasingly easy to access.
Build the habit of checking before you fill
Rather than reacting at the pump, check prices on a route you drive regularly and identify two or three reliably cheap stations. CarFile keeps an eye on this for you with a dedicated UK fuel prices tool, so you can see how current pump costs are trending without trawling multiple apps. For a deeper look at what actually moves prices, our guide to petrol prices in the UK breaks down the duty, VAT and crude-oil components that make up every litre.
Don't ignore the detour cost
Before you drive across town for cheaper fuel, do the quick maths. If a station is 4p cheaper but six miles further away (twelve miles round trip), a car returning 45 mpg burns roughly 1.2 litres getting there and back, costing well over a pound. On a 50-litre fill you would save £2 on price but spend more than half of it on the detour. The saving only makes sense if the cheaper station is genuinely on your route or very close.
How to Compare Fuel Types: Petrol, Diesel, Electric and Hybrid
Comparing forecourts is the quick win. The bigger, longer-term comparison is between fuel types, and this is where many drivers and fleets get the sums wrong because they fixate on the price per litre or per kWh rather than the cost per mile.
Petrol versus diesel
Diesel typically costs a few pence more per litre than petrol at the pump, but diesel engines are usually more efficient, especially on long motorway runs. For high-mileage drivers and fleets covering significant distances, diesel can still work out cheaper per mile despite the higher pump price. For low-mileage urban drivers, the efficiency advantage rarely offsets the price premium and the higher servicing costs, so petrol often wins.
Electric versus combustion
Electricity is where the comparison gets genuinely interesting. Charging at home on an off-peak overnight tariff can deliver a cost per mile dramatically lower than petrol or diesel, often a third or less. However, relying on public rapid chargers, particularly ultra-rapid units on motorways, can push the cost per mile much closer to petrol, and occasionally above it. So the honest answer to "is electric cheaper?" is: it depends entirely on where you charge.
Hybrids
Hybrids sit in between, offering improved efficiency in stop-start urban driving where the electric motor does most of the work, but smaller gains on long motorway journeys. They remove range anxiety while still cutting fuel use.
We have crunched all of these numbers in detail in our full fuel comparison for 2026, which compares petrol, diesel, electric and hybrid running costs side by side so you can see which makes sense for your mileage and driving pattern.
Comparing Fuel on a Cost-Per-Mile Basis
If you take only one idea from this article, make it this: the only fair way to compare fuel is pence per mile (ppm). It is the single figure that lets you compare a petrol hatchback, a diesel van and an electric saloon on a level playing field.
The calculation is straightforward:
- For petrol and diesel: divide the price you paid per litre by your car's fuel economy, adjusting units. A quick method is to multiply pence per litre by 4.546 (litres in a gallon) and divide by your real-world mpg. For example, at 150p per litre and 45 mpg, that is (150 × 4.546) ÷ 45 ≈ 15.2 pence per mile.
- For electric: divide the price per kWh by the car's efficiency in miles per kWh. At 8p per kWh overnight and 3.5 miles per kWh, that is just 2.3 pence per mile. At a 75p public rapid charger, the same car costs around 21 pence per mile.
The lesson is stark: the same electric car can be the cheapest or among the most expensive vehicles to run depending purely on where it charges.
The critical input is real-world economy, not the optimistic figure on the manufacturer's brochure. Most cars achieve noticeably less than their official WLTP numbers in everyday driving. The only way to know your true figure is to track it. Our free cost per mile calculator does the arithmetic for you, and the accompanying fuel cost per mile guide walks through worked examples for petrol, diesel and electric. To understand how fuel slots into your overall motoring budget, our car running costs page puts it alongside insurance, servicing and depreciation.
Comparing Fuel Costs as a Fleet Operator
For small fleets, fuel is often the single biggest controllable expense, and the savings from systematic comparison scale up fast. The principles above still apply, but a few extra tactics matter.
Track per-vehicle and per-driver efficiency
Two identical vans driven by two different drivers can return wildly different economy. Harsh acceleration, excessive idling, under-inflated tyres and unnecessary weight all erode mpg. By logging fuel spend and mileage per vehicle, you can quickly spot the outliers and coach the drivers responsible. Even a 5% improvement in fleet-wide economy translates directly into thousands of pounds saved.
Use fuel cards and bunkered pricing wisely
Fuel cards can secure a consistent network price and remove the administrative burden of collecting receipts, but they are only a saving if the network's pricing genuinely beats what your drivers could find locally. Compare the effective card price against local supermarket pricing before committing.
Centralise the data
The enemy of good fleet fuel management is scattered receipts and spreadsheets. Pulling every fill-up into one place makes patterns obvious. CarFile's expense tracking lets you log fuel against each vehicle and see cost-per-mile trends over time, and our wider fleet management guide sets out how disciplined tracking can cut total running costs by up to 30%.
Practical Tips to Lower Your Fuel Bill
Comparing fuel is only half the battle; using less of it is the other half. A few proven habits make a measurable difference:
- Keep tyres correctly inflated. Under-inflated tyres increase rolling resistance and can knock several percent off your economy.
- Remove excess weight and roof boxes. Both hurt efficiency, with roof boxes adding significant aerodynamic drag at motorway speeds.
- Drive smoothly. Gentle acceleration, reading the road ahead, and avoiding harsh braking are the biggest behavioural wins.
- Stick to sensible speeds. Fuel use climbs sharply above 60 to 65 mph.
- Service the car on schedule. A well-maintained engine runs more efficiently.
Our full list of 25 fuel-saving tips for UK drivers goes much deeper if you want to squeeze out every last mile per gallon.
Frequently Asked Questions
Q: What is the cheapest way to compare fuel prices near me?
A: Use a live fuel-price tool rather than driving around looking at forecourt signs. The Government's Fuel Finder transparency scheme is improving the availability of real-time data, and CarFile's UK fuel prices tool helps you track how local pump costs are moving. Always weigh any saving against the extra distance you would drive to reach a cheaper station.
Q: Is diesel cheaper to run than petrol?
A: It depends on your mileage. Diesel usually costs a little more per litre but delivers better economy on long journeys, so high-mileage and fleet drivers often pay less per mile. For low-mileage urban driving, petrol is generally the cheaper and simpler choice once you account for higher diesel servicing costs.
Q: How do I compare petrol and electric fairly?
A: Convert both to pence per mile. Divide your petrol price per litre by your real mpg (adjusting units), and divide your electricity price per kWh by your car's miles per kWh. Charging an EV at home overnight is usually far cheaper per mile than petrol, but frequent use of public rapid chargers narrows or even erases the gap.
Q: Why is my real fuel economy worse than the official figure?
A: Official WLTP figures are measured under controlled laboratory conditions. Real-world driving involves cold starts, traffic, hills, heavier loads and higher speeds, all of which reduce economy. Tracking your own fill-ups over time gives you a true average to use in any cost comparison.
Q: Does it ever pay to drive further for cheaper fuel?
A: Only if the cheaper station is on or very close to your route. A long detour burns fuel and time that can wipe out the saving. As a guide, a few miles out of your way for a 5p-plus per litre saving is usually worthwhile; a cross-town trip rarely is.
Conclusion: Compare Smarter, Not Harder
Learning to compare fuel properly is one of the highest-return habits any UK driver or fleet operator can build. The trick is to stop fixating on the headline pump price and start thinking in pence per mile, factoring in your vehicle's real-world economy, where you fill up or charge, and the journey itself. Do that consistently and the savings, whether £300 a year for a single driver or thousands for a fleet, look after themselves.
The easiest way to make this effortless is to let an app do the tracking and the maths for you. Get started with CarFile to monitor live UK fuel prices, log every fill-up against your vehicle, and see your true cost per mile at a glance, so every comparison you make is grounded in your own real data.