E10 vs E5 Petrol: Which Should You Use in the UK?
E10 vs E5 petrol — it's a comparison every UK driver should understand, especially since E10 became the standard unleaded petrol grade at forecourts across the country. The switch was introduced to reduce CO₂ emissions from petrol vehicles, but it left many drivers wondering whether their car can use it, whether it costs more in the long run, and whether they should seek out E5 super unleaded instead.
This guide breaks down the differences between E10 and E5 petrol, covering compatibility, fuel economy, price, environmental impact, and where to find each grade. For a broader overview of what E10 petrol is, see our E10 petrol explainer.
What Is E10 Petrol?
E10 petrol contains up to 10% bioethanol blended with 90% fossil petrol. The "E" stands for ethanol, and the number indicates the maximum percentage of bioethanol in the blend. Bioethanol is an alcohol-based fuel produced from crops such as wheat, corn, and sugar beet.
E10 has been the standard unleaded petrol grade at UK forecourts since the government mandated the switch. The Department for Transport introduced the change as part of the UK's strategy to reduce transport emissions, estimating that doubling the bioethanol content from 5% to 10% could reduce CO₂ emissions from petrol vehicles by around 750,000 tonnes per year — equivalent to taking roughly 350,000 cars off the road.
You'll find E10 at virtually every petrol station, including Tesco forecourts and Shell stations across the UK. Check petrol prices in London or prices in Birmingham to find the cheapest E10 near you.
What Is E5 Petrol?
E5 petrol contains up to 5% bioethanol and was the standard UK unleaded grade before the E10 switch. Since the change, E5 is now sold as "super unleaded" — the higher-octane premium petrol grade (typically 97–98 RON rather than the standard 95 RON of E10).
E5 super unleaded is available at most forecourts but typically costs 7–12p per litre more than standard E10 unleaded. It's stocked at major branded stations including Shell, BP, Esso, and many supermarket forecourts.
To compare prices across brands, check BP petrol prices or Asda petrol prices in your area.
E10 vs E5: Key Differences
| Feature | E10 (standard unleaded) | E5 (super unleaded) | |---------|-------------------------|----------------------| | Bioethanol content | Up to 10% | Up to 5% | | Octane rating (RON) | 95 | 97–98 | | Price per litre | Cheaper (standard price) | ~7–12p more per litre | | Fuel economy | Slightly lower (~1–2% less mpg) | Slightly better | | Vehicle compatibility | Most cars post-2011, some older models | Nearly all petrol cars | | CO₂ emissions | Lower (tailpipe + crop offset) | Higher | | Availability | All forecourts | Most forecourts (as super unleaded) |
Fuel Economy: Does E10 Give You Fewer Miles Per Gallon?
Yes, slightly. The RAC and the Department for Transport have both acknowledged that E10 petrol has a slightly lower energy density than E5, which means your car may return marginally fewer miles per gallon.
The estimated reduction in fuel economy is around 1–2% — roughly equivalent to losing 0.5–1 mpg for a car that normally achieves 50 mpg. For a typical driver covering 8,000 miles per year, this could mean using an extra 1–2 litres of fuel per month.
Whether this economy loss offsets the cheaper per-litre price of E10 depends on the price gap between E10 and E5 at your local forecourt. Given that super unleaded typically costs 7–12p more per litre, E10 remains the more cost-effective choice for most drivers, even accounting for the slight mpg reduction.
Our insights page tracks national average petrol prices so you can compare the cost difference between grades.
Vehicle Compatibility: Can Your Car Use E10?
The vast majority of petrol cars on UK roads are compatible with E10. The government estimates that around 95% of petrol vehicles can use E10 without any issues.
Cars that CAN use E10
- All petrol cars manufactured from 2011 onwards
- Most petrol cars from 2002 onwards
- Many older models — check the government's E10 compatibility checker at gov.uk
Cars that should NOT use E10
- Some pre-2002 petrol cars (particularly older models from certain manufacturers)
- Classic cars and vehicles with older fuel system components
- Certain specific models listed on the gov.uk checker
If your car is not E10-compatible, you should use E5 super unleaded instead. Using E10 in an incompatible vehicle can cause damage to fuel system seals and hoses over time, as bioethanol is more corrosive than fossil petrol at higher concentrations.
The AA and RAC both recommend using the government's official E10 compatibility checker on gov.uk before switching, especially for older vehicles.
Environmental Impact: Why the Government Chose E10
The primary reason for the E10 switch is CO₂ reduction. Bioethanol is a renewable fuel — the crops used to produce it absorb CO₂ as they grow, partially offsetting the emissions from combustion.
According to the Department for Transport:
- Doubling bioethanol content from 5% to 10% reduces the fossil carbon content of petrol
- The estimated annual CO₂ saving is approximately 750,000 tonnes across the UK petrol fleet
- This is equivalent to taking around 350,000 cars off the road in terms of emissions
The RAC Foundation has noted that while E10 is not a silver bullet for transport decarbonisation, it is a meaningful step that requires no vehicle modifications for the majority of drivers.
Cost Comparison: Is E10 or E5 Cheaper?
For most drivers, E10 is the cheaper option — both at the pump and over the full tank lifecycle.
Consider a typical fill-up of 50 litres:
| Fuel grade | Typical price per litre | Cost for 50 litres | |------------|------------------------|-------------------| | E10 (95 RON unleaded) | 140–150p | £70–£75 | | E5 (97–98 RON super unleaded) | 150–162p | £75–£81 |
Even accounting for the 1–2% economy reduction with E10, the per-mile cost remains lower than E5 for the vast majority of drivers. The extra cost of E5 (7–12p per litre) far outweighs the marginal fuel economy benefit.
To find the cheapest E10 or E5 forecourt near you, compare prices in Manchester, prices in Leeds, or your local area on our site.
Frequently Asked Questions
Is E10 or E5 better for my car?
For most modern petrol cars (2011 onwards), E10 is the recommended and most cost-effective fuel. E5 super unleaded is only necessary if your car is not E10-compatible, or if your vehicle's manufacturer specifically recommends higher-octane fuel. Using E5 in a car designed for 95 RON unleaded provides no performance or economy benefit that justifies the extra cost.
Can I mix E10 and E5 petrol?
Yes. Mixing E10 and E5 in the same tank is perfectly safe — the resulting blend will have an ethanol content somewhere between 5% and 10%, which is within the tolerance of any E10-compatible vehicle. If you're unsure about compatibility and E5 is not available, a single tank of E10 in an older car is unlikely to cause damage — just switch back to E5 at the next fill-up.
Where can I buy E5 petrol?
E5 is sold as super unleaded (97 or 98 RON) at most petrol stations in the UK, including Shell, BP, Esso, and many supermarket forecourts. It typically costs 7–12p per litre more than standard E10 unleaded. Use our site to compare prices at Sainsbury's forecourts or other brands near you.
Will E10 damage my older car?
E10 can cause damage to fuel system components in some older vehicles, particularly those manufactured before 2002. The higher bioethanol content is more corrosive to certain rubber seals and plastic components. Always check the government's E10 compatibility checker on gov.uk if you drive an older petrol car. If in doubt, use E5 super unleaded.
Does E10 reduce fuel economy?
Yes, by approximately 1–2%. The lower energy density of bioethanol means E10 contains slightly less energy per litre than E5. For a car achieving 50 mpg, this translates to roughly 0.5–1 mpg less. However, the cheaper per-litre price of E10 means it remains more economical for most drivers. See our fuel price data to compare costs in your area.