E10 vs E5 Petrol: Which Should You Use? Complete Guide

What Are E10 and E5?

The names refer to the ethanol content of the fuel. E10 contains up to 10% renewable ethanol blended with petrol, while E5 contains up to 5% ethanol. Both are unleaded petrol — the difference is purely in the proportion of bioethanol.

E10 replaced E5 as the standard grade of petrol (95 octane) at UK filling stations in September 2021. E5 is still available as the "super unleaded" or "premium" grade (97+ octane) at most forecourts, though it now costs significantly more.

Key Differences at a Glance

Is Your Car Compatible with E10?

Around 95% of petrol cars on UK roads are compatible with E10. As a general rule, if your car was manufactured from 2011 onwards, it will run perfectly well on E10. Many cars built before 2011 are also compatible — manufacturers have published compatibility lists, and you can check the government's official E10 compatibility checker.

Cars That Should Use E5 Instead

Some vehicles are not compatible with E10 and should continue using E5 super unleaded. These include:

• Classic and vintage cars — vehicles built before the early 2000s, particularly those with carburettors or older fuel system components.
• Some cars from 2000 to 2011 — certain models from this era have rubber seals, gaskets or fuel lines that can degrade with higher ethanol content. Check your manufacturer's guidance.
• Mopeds and small motorcycles — some older two-stroke engines are not designed for E10.
• Lawnmowers and garden equipment — many small engines used in garden tools are not E10 compatible and can suffer corrosion or fuel system damage.

If you accidentally put E10 in a non-compatible car, do not panic. A single tankful is unlikely to cause immediate damage, but you should avoid making it a habit. Switch back to E5 at your next fill-up.

The Price Difference: Is E5 Worth the Extra Cost?

As of early 2026, the price gap between E10 and E5 is typically 15 to 18 pence per litre. On a 50-litre fill, that works out at £7.50 to £9.00 more per tank. Over a year of fortnightly fill-ups, the extra cost of E5 adds up to around £195 to £234.

For most drivers with E10-compatible cars, there is no compelling reason to pay for E5 unless your vehicle specifically requires higher octane fuel (some performance cars recommend 97+ RON). The savings from using E10 are significant and the fuel meets all the same British Standards.

Fuel Efficiency: Does E10 Use More Fuel?

Ethanol contains less energy per litre than pure petrol. Because E10 has more ethanol, it delivers slightly fewer miles per litre than E5. The Department for Transport estimates that E10 reduces fuel economy by around 1 to 2 percent compared to E5.

In practical terms, this means you might see your fuel consumption increase by 0.5 to 1 mile per gallon. For most drivers, this small efficiency loss is far outweighed by the 15 to 18 pence per litre saving. You would need to see a much larger efficiency difference — closer to 10% — for E5 to break even on cost.

The Environmental Angle

The introduction of E10 was primarily an environmental measure. Bioethanol is produced from crops and plant materials, making it a renewable fuel source. The government estimates that the switch to E10 reduces CO2 emissions from petrol cars by around 750,000 tonnes per year — equivalent to taking 350,000 cars off the road.

However, the environmental picture is not entirely straightforward. Growing crops for bioethanol requires land, water and energy. There is ongoing debate about the net carbon benefit when full lifecycle emissions are considered. Nonetheless, E10 is broadly accepted as a modest step towards lower-carbon road transport while the transition to electric vehicles continues.

Can You Mix E10 and E5?

Yes, you can mix E10 and E5 in the same tank without any problems. If you have been using E5 and want to switch to E10, simply fill up with E10 next time. There is no need to drain the tank or take any special precautions. The fuels are fully miscible and your engine will not notice the difference.

E5 Availability: Will It Disappear?

There are no current plans to remove E5 from UK forecourts. It remains available as the super unleaded grade at the vast majority of filling stations. However, as the proportion of older, E10-incompatible cars on the road decreases, there may be less commercial incentive for retailers to stock it at every location. For now, it is widely available.

Which Should You Choose?

The decision is straightforward for most drivers:

• Use E10 if your car is compatible (2011 onwards, or check your manufacturer's list). It is cheaper, widely available, and slightly better for the environment.
• Use E5 if your car is not compatible with E10, if you have a classic or vintage vehicle, or if your car's manufacturer specifically recommends 97+ RON fuel.
• Do not pay for E5 "just in case" — if your car is listed as E10 compatible, there is no benefit to using the more expensive fuel.

You can compare E10 and E5 prices in your area using our fuel price comparison tool. Filter by fuel type to see exactly how much you could save by switching.

Frequently Asked Questions

Does E10 damage engines?

Not in compatible vehicles. E10 has been used extensively across Europe and the United States for years without issues. If your car is designed for E10 (as almost all modern cars are), it will run perfectly normally.

Is E5 the same as super unleaded?

At UK forecourts, yes. Since E10 became the standard grade, E5 is now sold as the "super unleaded" or "premium unleaded" option, typically at 97 to 99 RON. Before September 2021, standard unleaded was also E5.

Will using E10 void my warranty?

No. If your manufacturer confirms your vehicle is E10 compatible, using E10 will not affect your warranty. The fuel meets all required British and European standards. Check our FAQ page for more common questions.