Fuel Types & Quality Super Unleaded

What's the difference between unleaded and super unleaded?

Q: What's the difference between unleaded and super unleaded?

Standard unleaded is 95 RON (sold as E10 in the UK), while super unleaded is 97–99 RON (sold as E5). The higher octane rating in super unleaded resists engine knock better, which benefits high-performance or high-compression engines. For most everyday cars, standard 95 RON unleaded is sufficient and the extra cost of super unleaded is unlikely to be recovered in performance or economy gains.

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The key difference is octane rating: standard unleaded (E10) is 95 RON, while super unleaded is 97–99 RON. A higher octane rating means the fuel resists 'knocking' better, which can benefit high-performance engines — but makes no meaningful difference to most everyday cars.

Octane Rating Explained

What RON means: RON (Research Octane Number) measures a fuel's resistance to premature ignition, known as 'knocking' or 'pinging'. Higher RON fuels can withstand greater compression before igniting. 2

Standard unleaded: 95 RON: Standard unleaded in the UK is sold as E10, containing up to 10% bioethanol. It meets the minimum 95 RON specification required for most petrol engines. 3

Super unleaded: 97–99 RON: Super unleaded (sold as V-Power, Ultimate, or Momentum 99 depending on brand) typically hits 97–99 RON and contains up to 5% ethanol (E5), making it the higher-grade option. 2

When Super Unleaded Actually Helps

High-performance engines: Sports and performance cars with high-compression engines are specifically tuned to exploit higher octane fuel, and can see genuine power and efficiency gains from super unleaded.

Manufacturer recommendations matter: Check your owner's manual. If your car specifies 97 RON or higher, using 95 RON standard unleaded can cause the engine management system to retard ignition timing, reducing performance and economy. 4

Older or classic vehicles: Some older vehicles are incompatible with E10 fuel due to rubber seals and plastics that degrade with higher ethanol content. Super unleaded (E5) is a safer choice for these cars. 3

The Cost Difference

Super unleaded costs more: Super unleaded typically costs 10–15p per litre more than standard unleaded. For most drivers, this premium is not recovered through fuel economy improvements. 1

Additive packages also differ: Premium fuels from branded stations include enhanced cleaning additives that can help maintain fuel injectors and combustion chambers over time, though the benefit is gradual rather than immediate.

Which Should You Use?

Most drivers: stick with 95 RON: If your car's handbook specifies 95 RON, standard unleaded is perfectly fine and will not harm your engine. Paying extra for super unleaded in this case is unlikely to deliver any benefit.

Compare prices before filling up: If you do use super unleaded, prices vary considerably between stations. CheckFuelPrices shows live super unleaded prices at thousands of UK stations so you can find the best value nearby. 1