E10 vs E5 petrol: what is the difference and is super unleaded worth it?

Since September 2021, the normal grade of petrol in Great Britain has been E10. That is unleaded petrol with up to 10% ethanol mixed in. E5 has up to 5% ethanol and is sold as super unleaded or premium petrol, at 97 to 99 octane. Today E10 costs – a litre on average and E5 costs –. That is a gap of – a litre.

Does my car need E5?

Nearly every petrol car built since 2011 runs fine on E10, and so do most cars from the late 1990s onwards. The Government has an online checker for the exceptions. These are mainly some older Volkswagens, Fords and Rovers, classic cars, and a lot of mopeds and garden machines. If your handbook says 95 RON unleaded, E10 is fine. Some performance and turbo engines are built for 97 to 99 RON. They lose a little power and economy on 95, and those are the cars where E5 makes sense.

What E10 does to fuel economy

Ethanol holds less energy than petrol, so E10 gives you about 1% to 2% fewer miles per litre than the old E5 standard grade did. At a – premium, E5 would need to give you about several per cent better economy to pay for itself in an ordinary car. It does not.

Where E5 is cheapest

Supermarkets sell E5 at a smaller mark-up than branded forecourts. A few independent forecourts price the two grades within a few pence of each other. Every forecourt page on this site lists all the grades it sells, and the super unleaded page ranks the cheapest E5 in the country.