E10 vs E5 petrol: which should you use?

Since E10 became the standard unleaded petrol in the UK in September 2021, drivers have had a choice: fill up with the cheaper E10 or pay more for E5 (super unleaded). But what's actually different, and does it matter?

What the numbers mean

E10 contains up to 10% bioethanol blended with petrol. E5 contains up to 5%. Bioethanol is a renewable fuel made from crops, and blending it into petrol helps reduce carbon emissions. The "E" stands for ethanol, and the number is the maximum percentage.

The price difference

E5 (super unleaded) typically costs 15-20p per litre more than E10. On PumpSaver, you can toggle between fuel types to see the exact difference in your area. On a 50-litre tank, that's £7.50-£10 more per fill-up — a significant premium.

Does E10 affect fuel economy?

Ethanol contains less energy per litre than petrol, so E10 can give slightly worse fuel economy — roughly 1-2% less than E5. However, this small efficiency loss is far outweighed by the price savings. You'd need to see about a 15% fuel economy drop to justify paying for E5 on cost grounds alone.

Compatibility

Most cars built after 2011 are fully compatible with E10. Older vehicles, some classic cars, and certain motorcycles may need to use E5 to avoid potential issues with fuel system components. Check the government's online vehicle checker if you're unsure.

The verdict

For the vast majority of drivers, E10 is the sensible choice. It's significantly cheaper and the minor fuel economy difference doesn't justify the premium. Only use E5 if your vehicle specifically requires it. PumpSaver shows prices for both so you can always compare.