Guides & Glossary

Fuel Guide

A simple UK guide to petrol, diesel, E10, E5, premium fuel and the small choices that affect running cost.

Quick answer

Most modern petrol cars can use E10. If your vehicle is not compatible with E10, use E5 super grade. Diesel drivers should use the correct diesel grade and avoid misfuelling. Premium fuel is not automatically better value unless your vehicle recommends or benefits from it.

E10 petrol Usually the standard petrol choice for most modern petrol cars in the UK.

E5 petrol Usually sold as super grade petrol and useful for older or incompatible vehicles.

Diesel For diesel vehicles only. Always check before filling to avoid costly misfuelling.

What the pump labels mean

UK forecourts use labels to help drivers choose the correct fuel. The letter shows the fuel family and the number shows the maximum renewable fuel blend.

E10Petrol containing up to 10% ethanol. This is the standard petrol grade for most modern petrol vehicles.

E5Petrol containing up to 5% ethanol. Often sold as super grade petrol and commonly used by vehicles that cannot use E10.

B7Diesel containing up to 7% biodiesel. This is the common diesel label at UK pumps.

E10 vs E5: which should you use?

For most drivers, E10 is the normal choice. Most petrol vehicles on UK roads can use E10, and cars built since 2011 are generally compatible. If your car is older, imported, specialist, classic, or you are not sure, check compatibility first.

Use E10 if:

Your vehicle is compatible with E10.
You want the usual standard petrol option.
Your handbook or manufacturer does not require super grade fuel.

Use E5 if:

Your vehicle is not E10 compatible.
You drive an older, classic or specialist petrol vehicle.
Your manufacturer recommends higher octane fuel.

Is premium fuel worth it?

Premium fuel can be useful for some performance engines or vehicles where the manufacturer recommends higher octane petrol. For many everyday cars, the extra cost may not deliver enough benefit to make it better value.

Best rule

Follow your vehicle handbook first.

Value check

If premium fuel costs more, compare whether MPG or performance actually improves for your driving.

Diesel basics

Diesel vehicles must use diesel fuel. Putting petrol into a diesel vehicle, or diesel into a petrol vehicle, can cause serious damage. If you realise the mistake before driving, do not start the engine. Ask the forecourt or a recovery service for help.

AdBlue

Many modern diesel vehicles also use AdBlue to reduce emissions. AdBlue is not fuel and must go into the separate AdBlue tank, not the diesel tank.

Common fuel mistakes

“Premium is always better”

Not always. It depends on the engine and whether the extra cost produces a real benefit.

“All petrol cars can use E10”

Most can, but not all. Older and specialist vehicles may need E5.

“E5 and E10 labels are brand names”

No. They describe ethanol content in petrol.

“AdBlue is a diesel additive”

It is used by emissions systems, but it does not go into the diesel tank.

Quick fuel-saving tips

Check tyre pressure when tyres are cold.
Remove unused roof boxes and heavy items.
Accelerate smoothly and avoid unnecessary hard braking.
Compare nearby prices before filling up.
Avoid driving far out of your way unless the saving is worth the extra fuel.

Useful official links

For vehicle-specific compatibility, always check the official checker or your vehicle handbook.

GOV.UK E10 petrol explained ↗ Check E10 compatibility ↗ Fuel pump labels ↗