Fuel Types & Quality
Petrol vs Diesel
Is petrol or diesel cheaper?
CheckFuelPrices Editorial
Expert Written • 4 industry sources
Petrol is almost always cheaper per litre than diesel at UK forecourts, typically by 3–8p per litre. However, diesel engines are more fuel-efficient, so the cheaper fuel at the pump does not automatically mean a lower cost per mile.
Pump Price: Petrol Wins
Petrol costs less per litre:
Across UK stations, petrol consistently retails at a lower pence-per-litre price than diesel. You can see the live gap between petrol and diesel at every station near you on CheckFuelPrices.
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The gap varies by station type:
Supermarkets like Asda and Tesco typically offer the smallest spread between petrol and diesel prices, while branded stations such as BP and Shell can show a wider gap.
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Cost Per Mile: Diesel Often Wins
Diesel delivers better mpg:
A diesel engine typically returns 15–30% more miles per gallon than a comparable petrol engine, which can offset the higher price per litre on longer journeys.
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Motorway drivers benefit most from diesel:
The mpg advantage of diesel is most pronounced at a steady motorway speed. Urban stop-start driving narrows that gap considerably, making petrol more cost-competitive in town.
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E10 petrol is slightly less efficient:
Standard unleaded is now E10, meaning it contains up to 10% ethanol, which has lower energy density than pure petrol and can reduce fuel economy by around 1–2% compared to the older E5.
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Other Costs to Factor In
Diesel cars cost more to buy:
Diesel vehicles carry a purchase premium over equivalent petrol models, so high mileage is usually needed before fuel savings recoup that difference.
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Road tax and running costs differ:
Diesel cars registered after April 2017 may attract higher first-year VED rates due to NOx emissions. Servicing costs and AdBlue refills can also add to the overall running cost of a diesel.
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Check Live Prices Before You Fill Up
Prices vary station to station:
The petrol-vs-diesel price gap at your local stations may differ from the national average. Checking live data before you drive out can save you several pounds per fill.
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Use CheckFuelPrices to compare:
CheckFuelPrices shows live petrol and diesel prices at 4,000+ UK stations, updated every 30 minutes, so you can see exactly what both fuels cost near you right now.
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Sources
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