E10 Petrol: Is Your Car Compatible and Should You Use It?

E10 is petrol blended with up to 10% bioethanol — ethanol derived primarily from agricultural crops (wheat, sugar beet, and corn). The 'E10' designation refers to the ethanol percentage: E5 contained 5%, E10 contains up to 10%.

The UK government mandated the switch from E5 to E10 as the standard unleaded petrol grade in September 2021, following similar moves in France (2018), Germany (2011), and many other European countries. The rationale is environmental: bioethanol burns with lower net CO2 emissions because the carbon released was recently absorbed by the crops used to produce it.

The Department for Transport estimated the switch would save approximately 750,000 tonnes of CO2 per year — equivalent to removing around 350,000 cars from the road annually.

Under EU labelling rules (retained in UK law post-Brexit), petrol nozzles are colour-coded: E10 nozzles are green (or black with a green top), while E5 Super (97/98 octane) nozzles are black. Look for the 'E10' label inside the green nozzle handle at any UK forecourt.

The vast majority of cars on UK roads are E10-compatible. The government estimates that over 95% of petrol vehicles currently registered in the UK can use E10 without issues.

Compatible vehicles: All cars manufactured after 2011 are required by EU legislation to be E10-compatible. Most cars manufactured after 2000 are also compatible, though this is less universal. The government's official E10 compatibility checker (at gov.uk/check-vehicle-details, also accessible via the DVLA) covers almost all vehicles registered in the UK and gives a definitive answer for your specific make and model.

Potentially incompatible vehicles include: - Cars manufactured before 2000 (many, not all) - Classic cars and kit cars, particularly those with original fuel system components - Some 50cc and 125cc mopeds and scooters - Some older motorbikes, particularly pre-2002 models - Agricultural and marine engines - Small engines in lawnmowers, generators, and garden machinery

The concern with incompatible vehicles is that ethanol can degrade certain rubber seals, fuel hoses, and some metals used in older fuel systems. It can also be corrosive to some fuel tanks and carburettors. The risk is not instantaneous — a single fill of E10 in an incompatible vehicle is unlikely to cause immediate damage — but sustained use over time can cause problems.

Ethanol contains less energy per litre than petrol. E10's energy content is approximately 1–3% lower than E5, which means E10 gives slightly lower fuel economy — you'll use slightly more E10 to travel the same distance.

This energy content difference manifests as a 1–3% reduction in MPG when switching from E5 to E10. For a driver averaging 40 MPG on E5, E10 might deliver 38.8–39.6 MPG instead. The real-world impact on fuel costs is small — on an annual fuel bill of £1,500, a 2% reduction in economy costs around £30/year extra in fuel.

However, E10 is generally priced the same as E5 was (it's the standard grade), and E5 Super costs 10–15p per litre more than E10. So if you're choosing between E10 and E5 Super purely on cost: - If your car is E10-compatible, use E10 — despite the slight economy penalty, it's cheaper overall - If your car requires E5 Super (incompatible with E10), you have no choice and will pay the premium - If you're chasing maximum performance in a high-performance petrol engine, E5 Super's higher octane rating may give a marginal power benefit in cars with variable ignition timing

E5 Super (also called Super Unleaded, 97/98 octane, or Premium) is a higher-grade petrol containing no more than 5% ethanol. It was re-designated as the 'protection grade' petrol when E10 became the standard, ensuring that vehicles incompatible with E10 still have a fuel option available at UK forecourts.

By law, petrol stations with sufficient throughput must stock both E10 and E5 Super. This means E5 Super should remain available at all major forecourts indefinitely. However, at smaller rural stations with lower volume, E5 Super availability may be more limited — the regulations require it at stations selling more than a defined minimum volume.

E5 Super costs 10–15p per litre more than E10. For a 50-litre fill, that's £5–7.50 more per fill. If your car is E10-compatible, this premium is not justified — stick to E10. If your car requires E5 Super (classic car, pre-2000 vehicle, incompatible motorbike), the premium is unavoidable and worth paying to avoid fuel system damage.

A useful tip: some drivers of high-performance vehicles use E5 Super in the mistaken belief that the higher octane rating significantly benefits their engine. Modern engines with variable ignition timing systems do adapt to higher octane fuel and can produce marginally more power, but the fuel economy improvement is minimal and rarely justifies the premium cost.