Think premium petrol is always better for your car? For most drivers, that’s one of the biggest and most expensive motoring myths around.
Every day, millions of motorists pull into petrol stations across Britain, glance at the pumps and make a decision that feels sensible. “I’ll treat the car to the premium stuff.” After all, it costs more, so surely it must be better? Well… not necessarily.
In fact, if your car only requires regular 95 RON petrol, you could be spending an extra £150 to £200 every year for little or no measurable benefit. Over five years, that’s enough to pay for a major service, a fresh set of premium tyres, a family weekend away, or simply a lot more fuel.
So let’s separate fact from fiction and bust one of motoring’s most persistent myths.
What Is Premium Petrol?
Walk onto almost any UK forecourt and you’ll find two grades of petrol. Regular unleaded is typically rated at 95 RON, while premium or super unleaded is usually 97 to 99 RON, depending on the retailer. The assumption is obvious. Premium sounds… well… premium.
Many drivers believe it delivers more power, better fuel economy, a cleaner engine and longer engine life. Some of that is true. Most of it isn’t.
What Does RON Actually Mean?
RON stands for Research Octane Number. It isn’t a measure of how much energy is contained within the fuel. Higher octane petrol doesn’t contain extra horsepower waiting to be unleashed. Instead, octane measures how resistant the fuel is to engine knock or pre-ignition.
Modern high-performance engines often run higher compression ratios or increased turbo boost. Those engines need fuel that remains stable under greater pressure before the spark plug fires. That’s exactly what higher octane fuel provides.
Think of octane as the fuel’s ability to stay calm under pressure. Some engines need that extra resistance. Many don’t.
Does Your Car Actually Need Premium Fuel?
This is the question that really matters. Manufacturers spend years calibrating engines around a specific fuel grade. If your owner’s handbook recommends 95 RON, that’s what the engine was designed to run on.
Cars such as a Toyota Corolla, Nissan Qashqai, Kia Sportage, Hyundai Tucson or Volkswagen Polo are engineered to perform exactly as intended on standard unleaded. Pouring 99 RON into them doesn’t suddenly transform them into performance cars.
However, there are genuine exceptions. Cars such as the Volkswagen Golf GTI Clubsport, Honda Civic Type R, Porsche 911, Toyota GR Yaris and BMW M models often recommend or require higher octane fuel because their engines are specifically designed to exploit it.
In those cases, premium fuel isn’t a luxury. It’s the correct fuel.
Does Premium Petrol Improve Fuel Economy?
This is probably the biggest myth of them all. You’ll often hear drivers say premium petrol gives them better miles per gallon. Maybe. The real question is whether it gives enough improvement to justify paying more.
Let’s do the maths. Suppose regular petrol costs £1.45 per litre and premium costs £1.60. That’s roughly 10 per cent more expensive. If your car normally returns 40mpg, premium fuel would need to improve your economy to around 44mpg just to break even.
Most ordinary 95 RON engines simply don’t achieve anything like that. Many show no measurable improvement at all.
Drive around 10,000 miles a year and you’ll use approximately 1,136 litres of petrol. Paying an additional 15p per litre works out at roughly £170 extra every year. Keep the car for five years and you’ve spent around £850. That’s a lot of money for a benefit you probably never received.
Does Premium Fuel Clean Your Engine?
Unlike the octane myth, this one does contain a grain of truth. Many premium fuels include enhanced detergent packages that help reduce deposits on fuel injectors and other parts of the fuel system.
That’s a genuine benefit. The question is whether it’s worth paying an extra five to eight pounds every time you fill the tank. Personally, I don’t think it is.
A much more sensible compromise is to use premium every couple of months, or before a long motorway journey, if you like the idea of giving the fuel system an occasional clean.
You’ll enjoy most of the potential benefit without spending hundreds of pounds over the course of a year.
Is Supermarket Fuel Really Worse?
People love saying supermarket fuel is somehow inferior. The reality is rather less dramatic. All petrol sold in the UK has to meet strict British Standards.
The base fuel often comes from exactly the same refineries supplying the major oil companies. Where brands differ is mainly in their additive packages rather than the fuel itself.
So no, filling up at Tesco, Asda, Morrisons or Sainsbury’s isn’t going to destroy your engine. Your wallet might actually thank you.
There Is One Important Exception… Classic Cars
This is where my advice changes completely. If you own a classic car, premium fuel can genuinely be worthwhile. Not because of the octane. Because of the ethanol.
Regular unleaded in Britain is generally E10, containing up to ten per cent ethanol. Premium petrol is usually E5, containing no more than five per cent. Older fuel systems often weren’t designed for modern ethanol blends.
Ethanol absorbs moisture from the atmosphere and, over long periods, that moisture can contribute to corrosion inside tanks, fuel lines and carburettors. It can also accelerate deterioration of older rubber hoses, seals and gaskets.
That’s why organisations representing historic vehicles frequently recommend E5 wherever it’s available. The same applies if you’re putting a classic into winter storage.
Filling the tank with fresh E5 fuel, ideally alongside a quality fuel stabiliser, is generally a much better idea than leaving E10 sitting in the system for several months.
So if you own an E-Type, MGB, Triumph, Mini, Capri, or classic Porsche, premium fuel makes rather more sense.
So Which Fuel Should You Use?
The answer is refreshingly simple. If your owner’s handbook recommends 95 RON, use 95 RON. If it recommends 97 or 99 RON, buy premium.
If you own a classic, particularly one with an older fuel system or one that’s going into storage, premium E5 is usually the smarter choice.
Everything else is marketing, misconception and misplaced money.
The Bottom Line
Your engine doesn’t care how expensive the fuel was. It cares whether it’s the right fuel. For the vast majority of modern family cars, premium petrol is unlikely to deliver enough extra performance or fuel economy to justify the higher price.
Use the money you’ve saved on servicing your car properly instead. Fresh oil, quality tyres and correct maintenance will do far more for your car than filling it with expensive fuel it was never designed to use.
Sometimes the smartest motoring advice isn’t about spending more. It’s about spending wisely.
By ZARA KHAN
What do you think? Have you always filled up with premium petrol, or are you sticking with regular 95 RON? Let me know in the comments below, and don’t forget to subscribe to the BrownCarGuy YouTube channel for more myth-busting motoring advice, honest reviews and practical tips to help you get more from your car without spending more than you need to.
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