What is E10 fuel and how could it affect you and your car?

When filling up your car with petrol, you’re likely to be greeted with a choice of two green petrol pumps: E10 and E5. While the two fuels are not too dissimilar, there are some cars that are not compatible with E10, which is a type of unleaded petrol that was introduced in September 2021 to help reduce carbon emissions. So, here we explain everything you need to know about the fuel and how it can impact you and your car.

What is E10 fuel?

E10 is petrol that contains twice as much bioethanol as the E5 petrol that was previously the norm in the UK: 10%, as the name suggests. Bioethanol is a mixture of petrol and ethanol made from materials including low-grade grains, sugars and waste wood, with the idea being its use being to reduce carbon emissions.

This type of petrol has been sold elsewhere in Europe, including France and Germany, since 2009 and 2011 respectively, and all new cars sold in the UK since 2011 are able to run on it. However, even though fuel suppliers have legally been able to sell it in the UK since 2013, one reason they delayed the introduction was the concern that it can cause damage to older cars (you can find out more about this below). 

Should I use E10 or E5?

The RAC Foundation estimates that more than 634,000 cars on UK roads aren't compatible with E10, and 150,000 of these cars were built from the year 2000 onwards. Its director Steve Gooding said: "While some of those vehicles incompatible with E10 fuel will be historic models, many will be old but serviceable everyday runabouts that people on a tight travel budget rely on to get about." 

So, if you own an older petrol car and are concerned that it might not be compatible with E10, we recommend that you contact the manufacturer for confirmation or use the Government’s online E10 checker tool. You can also check the label on the inside of the car’s fuel-filler flap or the owner’s manual. If your car isn't compatible, you should only use E5.

What happens if I put E10 in a non-compatible car?

In the short-term, if you put E10 in a non-compatible car, it shouldn't have any noticeable problems. However, it can cause issues further down the line, because the higher bioethanol content in E10 petrol could dislodge deposits in older engines and fuel systems, causing blockages; it could also cause some seals, gaskets, metals and plastics to corrode, leading to hefty repair bills.

Why was E10 introduced? 

E10 petrol was introduced to help the Government meet its climate change targets. Bioethanol absorbs carbon dioxide, and it is estimated that every vehicle that switches to E10 will produce 2% less greenhouse gases. It’s also estimated the fuel could cut transport carbon dioxide emissions by 750,000 tonnes a year, which is the equivalent of removing 350,000 cars from UK roads.

Will E10 impact fuel economy?

E10 fuel is slightly less energy dense compared with E5, so car owners using E5 will get marginally better fuel economy than those using E10. However, the difference is minimal, plus it depends on the brand of fuel you’re using, the type of journey you’re making, and your driving style.

Will E10 impact performance?

If your car is compatible with E10 petrol, the fuel will not impact the performance of your vehicle and it should perform in the same way as E5.

Can you still buy E5? 

Although E10 petrol is now sold at all filling stations, high-volume outlets that sell more than three million litres of fuel a year are also allowed to stock ‘protection grade’ E5, so that owners of older cars will be able to fill up with this. E5 is expected to remain on sale until 2026, when its use will then be reviewed.

It's also worth noting that E5 petrol has been renamed super-unleaded and it usually costs 10-12p per litre more than E10. Although car owners using E5 will get marginally better fuel economy than those using E10, the additional cost of buying it could put a strain on drivers who are on a tight budget.

Is E10 for petrol and diesel?

E10 is a mixture of unleaded petrol and bioethanol, so it’s only suitable for petrol-powered vehicles. B7 is the equivalent of E10 for diesel-powered vehicles, because it contains a mixture of diesel and 7% bioethanol.

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