Fuel Types & Quality
E5 vs E10
What is E5 petrol?
CheckFuelPrices Editorial
Expert Written • 4 industry sources
E5 petrol is unleaded petrol blended with up to 5% bioethanol. It was the standard grade of petrol sold at UK forecourts until September 2021, when E10 became the new default.
What the 'E5' Label Means
Ethanol content:
The 'E' stands for ethanol and the number indicates the maximum percentage by volume. E5 contains up to 5% ethanol, with the remaining 95% being conventional unleaded petrol.
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British Standard compliance:
E5 petrol must meet BS EN 228, the same standard that governs all UK petrol quality, ensuring consistent performance and safety.
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Why ethanol is blended in:
Bioethanol is a renewable fuel derived from plant matter. Blending it into petrol reduces the carbon intensity of each litre compared to pure fossil fuel.
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E5 vs E10: What Changed in 2021
E10 became the default:
From September 2021, E10 — containing up to 10% ethanol — replaced E5 as the standard 'regular' unleaded grade at UK pumps to help cut transport CO2 emissions.
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E5 retained as the 'protected' grade:
The government required fuel retailers to keep selling E5 as the higher-octane 'super' unleaded grade (typically 97+ RON) to protect owners of older or incompatible vehicles.
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Slightly more energy per litre:
Because ethanol contains less energy than petrol, E5 delivers marginally more miles per litre than E10, though the difference is small — around 1–2% in real-world driving.
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Who Should Still Use E5?
Older and classic vehicles:
Cars built before 2002, many motorcycles, and some small-engine equipment such as lawnmowers may not be compatible with E10 and should use E5 to avoid fuel system damage.
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Check your vehicle:
The government's official E10 compatibility checker lists every make and model. If your car is flagged as incompatible, stick to E5 super unleaded.
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Higher price to expect:
Because E5 is now sold as the premium super unleaded grade, it typically costs 10–15p per litre more than standard E10 at the same station.
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Finding E5 at the Best Price
Availability varies by retailer:
Not every station stocks a super unleaded grade, so E5 can be harder to find than E10, particularly at smaller independents.
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Compare live prices before you fill up:
CheckFuelPrices shows live super unleaded (E5) prices at thousands of UK stations, updated every 30 minutes, so you can find the cheapest option near you.
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Sources
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