E10, E5 and B7 Fuel Explained: Which Fuel Is Right for Your UK Vehicle?
By FuelRoute · 2026-07-28
Pull up to most UK petrol stations these days and the pumps look a bit different. You’ll see circular labels on the petrol nozzles and square ones on the diesel. E10, E5, B7. They’re not marketing gimmicks. They tell you how much renewable fuel is mixed into the standard petrol or diesel.
These labels have been around for a few years now, but plenty of drivers still pause before they fill up. Here’s a straightforward look at what each one actually is, which vehicles they suit, and how to choose without second-guessing yourself every time you stop for fuel.
What the letters and numbers mean
The “E” stands for ethanol (or, more broadly, renewable content that can include other oxygenates). The number is the maximum percentage allowed. So E10 can contain up to 10% ethanol. E5 is limited to 5%.
Diesel uses “B” for biodiesel. B7 means the fuel can contain up to 7% biodiesel, usually in the form of FAME (fatty acid methyl ester made from vegetable oils or animal fats).
Petrol pumps carry circular labels. Diesel pumps use squares. Newer cars (from 2019 onwards) often have matching stickers near the fuel filler so you can double-check what the manufacturer approved.
E10 – the standard petrol you’ll find almost everywhere
Since September 2021 in Great Britain (and November 2022 in Northern Ireland), ordinary 95-octane unleaded has been E10. It’s the cheaper option at the majority of forecourts.
The idea is simple: blending in renewable ethanol cuts the amount of fossil petrol used and reduces overall CO₂ from petrol vehicles. Government estimates put the national saving at around 750,000 tonnes of CO₂ a year.
Most petrol cars cope with it without trouble. Official figures say roughly 95% of petrol vehicles on UK roads are compatible, and every new car sold since 2011 has had to be designed for E10. Many manufacturers approved their models from the late 1990s onwards.
There is a small catch on economy. Ethanol contains less energy than pure petrol, so most cars use a little more fuel – usually in the 1% to 3% range. The official line is about 1%, and most drivers won’t notice it on a single tank. Driving style, tyre pressures and traffic still make a bigger difference.
When E10 is not the right choice
Older cars and some classics can struggle. Ethanol is more corrosive to certain rubber seals, plastics and metals that were common before modern materials became standard. It also attracts water, which can lead to condensation in the tank if the car sits unused for long periods.
As a rough guide, cars registered before about 2002 are the ones most often advised to stick with E5. Some specific models from the early 2000s (certain direct-injection engines, for example) also appear on manufacturer exclusion lists. Motorcycles, mopeds under 50cc, boats, lawnmowers and generators often prefer the lower ethanol blend or pure petrol if you can get it.
The easiest way to check is the free government tool at gov.uk/check-vehicle-e10-petrol. You’ll need the make, and sometimes the model, engine size or year. If your car isn’t listed or you’re still unsure, the handbook or a specialist club is the next stop.
E5 – the higher-octane option that stays at 5% ethanol
E5 is what you’ll find sold as super unleaded or premium petrol (usually 97 RON or higher). It costs more – typically 8–12p a litre depending on the station and the day – but the ethanol content stays at 5% or less.
This is the safe default for any petrol vehicle that isn’t confirmed for E10. Classic car owners, riders of older bikes, and people with certain performance engines often stick with it for peace of mind. It also tends to store a bit better if the vehicle is left standing.
If you accidentally put E10 in an incompatible car, the usual advice is simply to top up with E5 once the tank is down a bit. One tank of the higher blend rarely causes lasting damage; prolonged use is the bigger risk. Mixing the two is fine in a compatible vehicle.
B7 – ordinary diesel with a renewable slice
B7 is the standard diesel sold at UK forecourts. It meets the EN 590 specification and can contain up to 7% biodiesel. Every modern diesel car, van and lorry is designed to run on it. Manufacturers confirmed years ago that B7 is fine across the diesel fleet.
You won’t usually have a choice at the pump – B7 is what comes out of the diesel nozzle. Higher biodiesel blends (B10 or above) or pure biodiesel are not sold for ordinary road vehicles at normal stations because they can affect fuel filters, seals and cold-weather performance. Some commercial sites offer HVO (hydrotreated vegetable oil), a different renewable diesel that can be used in many engines, but it’s still limited in availability and usually costs more.
For day-to-day driving, B7 behaves like the diesel you’ve always used. No special precautions are needed beyond normal fuel hygiene – keep the tank reasonably full in winter and change filters at the recommended intervals.
How to decide at the pump
- Petrol car from 2011 or later: E10 is the straightforward, cheaper choice.
- Older petrol car or anything you’re unsure about: check the government tool or handbook. Use E5 if there’s any doubt.
- Diesel: fill with B7.
- Classic, motorcycle, boat or garden machinery: lean towards E5 or the lowest ethanol option available.
- Look at the filler flap on newer vehicles – the labels are printed there for a reason.
Fuel economy differences between E5 and E10 are real but small compared with how you drive. The environmental gain from the higher ethanol blend is the main reason the standard changed. Clean air zones and ULEZ charges are based on the Euro emissions standard of the vehicle, not which blend you put in the tank.
That’s really all there is to it. Once you know what the circles and squares mean, choosing the right fuel becomes a quick glance rather than a moment of uncertainty.
Fuel price data context is derived from the UK Government Fuel Finder Scheme,
licensed under the Open Government Licence v3.0.
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