What is the difference between E10 and E5?

E10 petrol contains up to 10% ethanol, while E5 (super unleaded) contains up to 5%. Ethanol has less energy per litre than petrol, so E10 typically gives slightly worse fuel economy — around 1-2% lower MPG. E10 became the standard UK petrol in September 2021.

Is E5 worth the extra cost?

For most drivers, E10 is still cheaper overall despite the slight MPG reduction. E5 typically costs 8-12p per litre more. The extra cost usually outweighs the small economy benefit. However, some older or high-performance engines may run noticeably better on E5.

Can all cars use E10?

Most cars manufactured after 2011 are fully compatible with E10. Some older vehicles, particularly those made before 2002, may experience issues with rubber seals and fuel system components. Check the government E10 compatibility checker if unsure.

Does E10 damage engines?

E10 is safe for compatible vehicles. However, ethanol absorbs moisture, so if a car is left standing for long periods, E10 fuel can degrade faster. For classic or infrequently driven cars, E5 super unleaded is recommended.

Is E10 petrol bad for my car?

E10 is safe for the vast majority of cars built after 2011. Older cars (pre-2002 especially) may have fuel system components that are incompatible with the higher ethanol content. Check the government E10 compatibility checker at gov.uk. If in doubt, use E5 super unleaded.

CarCalcs

E10 vs E5 Calculator

Compare the annual cost difference between E10 standard petrol and E5 super unleaded.

Annual Mileage

Your MPG on E5 (UK)

Your current MPG on super unleaded

E10 Price

E5 (Super) Price

How We Calculate This

This calculator compares the true annual cost of E10 versus E5 petrol, accounting for the typical 2% MPG reduction caused by E10's higher ethanol content.

The Calculation

E10 MPG = Your MPG x 0.98 (2% reduction for higher ethanol)
E5 MPG = Your stated MPG (no adjustment)
Annual litres = (Annual miles / Adjusted MPG) x 4.54609
Annual cost = Annual litres x Price per litre

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Last updated: February 2026

All calculations are estimates. Actual figures may vary based on driving conditions, vehicle specifications, and other factors.