E10 vs E5 Premium Unleaded: Is it Worth the Extra Cost?
No - unless your car actually needs E5. Premium unleaded, which is the only way most forecourts sell E5, costs on average 17.3p a litre more than standard E10 across the 6,229 stations where we can compare the two side by side. The 1% to 2% economy difference between the blends is worth around 2p to 3p a litre at today's prices. For most drivers the maths is not close.
- Premium unleaded (typically E5) averages 17.3p a litre more than standard E10.
- The economy gain from lower ethanol content is worth roughly 2p to 3p a litre.
- Cars built after 2011, and most since 2001, are E10-compatible.
- Classics and some pre-2001 models genuinely need E5 - for them it is not a choice.
Understanding the difference between E10 and E5
In September 2021, E10 petrol became the standard grade of unleaded fuel in the UK, replacing the older E5 blend. The "E" stands for ethanol, and the number represents the maximum percentage of renewable ethanol in the mix. E10 contains up to 10% ethanol, while E5 contains up to 5%.
The change was driven by environmental targets to reduce CO2 emissions, but it left many drivers confused at the pump. Premium unleaded is now the only way to get E5 fuel at most forecourts. The question is what that upgrade is actually worth.
The measured price gap
Most articles quote a premium-unleaded premium of "10p to 15p" a litre. We measure it directly: at every station that publishes both a standard and a premium unleaded price, the premium averages 17.3p a litre more. The gap on premium diesel is almost identical at 17.2p.
| Fill size | Extra cost at 17.3p a litre | Per year at one fill a week |
|---|---|---|
| 40 litres | £6.92 | £359.84 |
| 50 litres | £8.65 | £449.80 |
| 55 litres | £9.52 | £495.04 |
| 60 litres | £10.38 | £539.76 |
That is the honest size of the decision. A driver filling a typical 50-litre tank weekly pays somewhere north of £400 a year to run E5 through a car that does not need it.
Does E5 give you better mileage?
Ethanol has slightly less energy density than pure petrol. Because E10 has more ethanol, you might see a small reduction in fuel economy, usually around 1% to 2%. At a standard-unleaded average of 161.2p a litre, that economy difference is worth roughly 2p to 3p a litre. Set that against the 17.3p price gap and the arithmetic closes the argument on its own: the tiny mileage gain from premium fuel will almost never offset the higher cost at the pump.
Is E10 safe for my car?
Almost all petrol vehicles built after 2011, and most since 2001, are fully compatible with E10. The government publishes a compatibility checker for specific models. If you drive a modern car, there is no mechanical reason to pay extra for E5 unless you are running a high-performance engine that specifically requires a higher octane rating - and in that case you are chasing the octane, not avoiding ethanol.
Which cars genuinely need E5
If you drive a classic car or a vehicle manufactured before 2001, the higher ethanol content in E10 can damage rubber seals, plastics and some metal components in the fuel system, and it draws moisture in a way older tanks were never designed for. For these drivers, premium E5 is not an upgrade; it is the correct fuel, and the 17.3p premium is simply a running cost of keeping an older car on the road. The same applies to a small number of listed-incompatible models from the early 2000s - the checker above is the authoritative list.
The verdict
For the overwhelming majority of UK drivers, standard E10 is perfectly fine and the cheapest way to drive is to find the lowest E10 price near you. Use FindPetrol to compare unleaded prices across supermarkets and independent forecourts so you never overpay for the fuel your car actually needs.
Comparing petrol prices before you fill up
Whichever grade you choose, the forecourt matters more than the badge: the same standard unleaded runs from well under to well over the 161.2p national average depending on where you stop. Local prices differ far more than most drivers expect - for a worked example, see current petrol prices in Birmingham. Check petrol prices near me by postcode, or see the full picture on our UK fuel prices page before you commit to a tank.
Frequently asked questions
Is premium unleaded always E5?
At most UK forecourts, yes: 97+ octane premium unleaded is the E5 blend, while the 95-octane standard pump is E10. A small number of premium products are now E10-based, so a car that must avoid ethanol needs the label checked, not just the premium price.
Will using E10 damage a car that should have E5?
Not from a single tank by accident, but repeated use in an incompatible car risks degrading seals and fuel lines over time. If the government checker lists your car as incompatible, stick to E5.
Does premium fuel clean your engine?
Many premium grades carry a higher additive treat rate, which can help keep injectors clean - but standard fuel already contains mandatory detergent additives. Our separate guide to premium fuels and engine cleaning covers the detail.
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