Is Premium Fuel Worth It? Super Unleaded vs Regular

Premium fuels differ from standard in two main ways:

• Higher octane rating (petrol). Standard unleaded is 95 RON. Super unleaded is typically 97–99 RON. Higher octane allows more aggressive ignition timing in engines designed for it, producing more power and slightly better efficiency.
• Enhanced additives. Premium fuels contain extra detergent and cleaning additives designed to reduce carbon build-up in the engine, fuel injectors, and intake valves.

For diesel, premium versions have a higher cetane number (the diesel equivalent of octane) and similar cleaning additives.

Premium fuel genuinely benefits your car in these situations:

• Your car requires 98 RON. Some performance and sports cars (Porsche, BMW M-series, AMG, certain Audi RS models) are designed for higher-octane fuel. Check your owner’s manual — if it says “98 RON required” or “98 RON recommended”, use it. Running on 95 RON triggers the knock sensor, which retards timing and reduces both power and efficiency.
• Turbocharged engines that recommend it. Many modern turbocharged cars (even non-performance models) will see a small but measurable improvement in power and economy on 97–99 RON fuel.
• Pre-2011 cars not compatible with E10. Super unleaded (E5) contains less ethanol than standard E10. If your car is not compatible with E10, you should use E5 super unleaded instead. Check E10 compatibility →

For the majority of UK cars, premium fuel is an unnecessary expense:

• Your car is designed for 95 RON. If your manual says 95 RON (which most do), higher-octane fuel will not improve performance. The engine cannot take advantage of the higher octane because it isn’t designed to adjust its timing.
• Older naturally-aspirated engines. These engines have fixed compression ratios and won’t benefit from higher octane.
• “Cleaning” claims for modern cars. All fuel sold in the UK already contains a minimum level of detergent additives required by law. Modern fuel injection systems are less prone to the carbon build-up issues that premium additives claim to address.

At 10p extra per litre, you’d spend roughly £250–£350 more per year on premium fuel. That money is better saved by simply finding a cheaper station.

Compare brand fuel prices →

Premium diesel (Shell V-Power Diesel, BP Ultimate Diesel) has a higher cetane number for smoother, more complete combustion. The claimed benefits include:

• Slightly improved fuel economy (1–3%)
• Reduced carbon deposits in fuel injectors
• Quieter engine operation
• Marginally more power

Independent testing suggests the economy improvement is real but small — typically 1–2%. At 10p extra per litre, you’d need at least a 7% improvement to break even. For most diesel drivers, the maths doesn’t add up.

Read our complete diesel guide →

• Check your manual. If it says 95 RON, standard unleaded is all you need.
• If it says 98 RON (or “super unleaded recommended”), use premium — it will genuinely improve performance and may improve economy enough to offset the cost.
• E10 incompatible? Use E5 super unleaded as your standard fuel.
• Everyone else: Save your money and fill up at a cheaper station instead.

The price difference between a cheap and expensive station for the same fuel is often larger than the difference between standard and premium at one station. Compare before you fill.