Is Premium Fuel Worth It?

Every large forecourt offers a choice: standard unleaded or diesel, and a pricier "premium" alternative — super unleaded petrol, or a branded premium diesel such as Shell V-Power or BP Ultimate. The premium pumps typically cost noticeably more per litre, and the marketing promises more power, better economy and a cleaner engine. So is it money well spent? For most drivers, the honest answer is: probably not. For some, it genuinely is. Here's how to tell which camp you're in.

What you're actually buying

Premium petrol and premium diesel are premium in different ways. With petrol, the headline difference is the octane rating. Standard UK unleaded is 95 RON (and, since September 2021, is E10 — up to 10% bioethanol). Super unleaded is typically 97 to 99 RON and is sold as E5, with a lower ethanol content. A higher octane rating means the fuel resists premature ignition ("knock") under compression, which allows engines designed for it to run more aggressive ignition timing and boost.

With diesel, there is no octane story. Standard and premium diesel both meet the BS EN 590 standard; what the premium product adds is a more concentrated detergent and additive package, intended to clean injectors, reduce deposits and, in some formulations, suppress foam and protect against corrosion. The base fuel is essentially the same.

Which engines actually benefit?

Octane only helps an engine that is built — or tuned — to exploit it. High-performance and many turbocharged engines have knock sensors and adaptive ignition timing, and their manufacturers may specify or recommend 97+ RON fuel. In those cars, super unleaded can deliver the performance the engine was designed for, and running the minimum recommended octane matters. Check your fuel filler flap or handbook: if it says 98 RON recommended, that advice is worth following.

A typical family hatchback designed for 95 RON, on the other hand, simply cannot use the extra octane. It won't be damaged by super unleaded, but back-to-back tests by motoring organisations have generally found little or no measurable benefit in ordinary cars. Any tiny economy gain is unlikely to offset a per-litre premium that is often substantial — you can see the real gap between grades in your area on our fuel prices pages.

The case for premium diesel

Premium diesel is a subtler judgement. The additive packages are real, and keeping injectors clean matters more in modern common-rail diesel engines than many drivers realise. Some mechanics suggest an occasional tank of premium diesel — or a bottle of a reputable fuel system cleaner — for cars that mostly do short urban journeys. But standard diesel already contains detergent additives, and a healthy engine doing a normal mix of driving will usually run indefinitely on standard fuel without trouble. Using premium diesel every fill is a comfort purchase more than a necessity for most drivers.

A sensible strategy

A pragmatic approach looks like this. First, follow your handbook: if your car specifies high-octane fuel, use it — that's not a premium, it's a requirement. Second, if your car needs E5 because it isn't E10-compatible (see our E5 vs E10 guide), super unleaded is your standard fuel by default. Third, if neither applies, put the money you'd spend on premium towards simply buying standard fuel more cheaply.

That last point is worth dwelling on. The price spread between forecourts in the same town is frequently larger than any plausible benefit from a premium grade, so shopping around does more for your running costs than trading up at an expensive station. Use the station search to sort nearby forecourts by price, watch for price drops near you, and if your schedule is flexible, check the best day to buy fuel in your area.

The bottom line

Premium fuel is worth it when your car's manufacturer says it is — high-performance engines specifying 97+ RON, or vehicles that must avoid E10. It can also be a reasonable occasional treat for a hard-worked diesel. For everyone else, standard E10 petrol or standard diesel from a competitively priced forecourt is the smart buy, and the premium pump is mostly paying for marketing. Whatever grade you use, note that premium prices vary between stations just like standard ones — many sites report their super unleaded and premium diesel prices, which you can compare in our station directory.