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Is premium unleaded worth the extra money?

Premium fuels claim to provide increased performance and fuel economy - read our guide to find out whether it’s worth the extra money

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When filling up your car at the local service station, you may have seen names for premium unleaded petrol like ‘V-Power’, ‘Supreme’ or ‘Ultimate’. What differences do they offer, and are there any advantages in paying extra for them?

These fuels claim to offer increased performance and fuel economy in the right conditions and with the right car, so read our guide to premium unleaded petrol to find out whether it’s worth the extra money. 

What is premium unleaded petrol? 

All petrol fuels have what is called a research octane number (RON), which denotes how well the fuel burns. Regular unleaded in the UK follows the EU standard (and will continue to do so despite Brexit) and has a minimum RON of 95.

Premium unleaded is usually more refined than regular unleaded, with a higher RON – usually from 96 to 99. Higher octane fuel is harder to ignite because it requires more compression than low octane fuels, but it burns better. Premium fuels also often have additives and detergents to keep the inside of the engine clean.

Higher octane fuels are supposed to be more fuel efficient as they require less fuel to create the same amount of power as lower octane fuels. High-performance vehicles typically have higher compression ratios in their engines which respond better to higher octane fuel, meaning that they will give better performance running on premium unleaded. 

Another difference between regular unleaded and premium unleaded is the amount of ethanol contained in the fuel, which may be an important factor for your car. We cover this below.

Petrol companies have different names for their premium fuel, including: 

  • BP Ultimate Unleaded 
  • Shell V-Power 
  • Texaco Supreme Unleaded 97 
  • Total Excellium Unleaded 
  • Esso Synergy Supreme+ 

How does premium unleaded petrol affect performance and fuel economy? 

Most modern petrol-engined cars are designed to use regular unleaded as their default fuel. Running your car on premium unleaded is unlikely to produce any improvement in performance, although may see a small improvement in fuel economy.

More notable differences are likely to be seen in high-performance cars, which designed to run on high-octane petrol. These engines will suffer reduced performance and fuel economy if you run them on regular unleaded. 

Some high octane fuels have cleaning additives or detergents that can help to keep the engine clean and run better so this may help to clean out your engine. But for prolonged use, you’re unlikely to see a marked return on investment unless premium fuel is specifically advised by the manufacturer. 

Does premium unleaded petrol lower emissions? 

In theory, premium unleaded petrol should decrease emissions as the fuel is designed to burn more efficiently and therefore less fuel is required. However, depending on driving style and how well suited premium unleaded is to your car, the cost saving in relation to emissions may be minimal. 

Is premium unleaded an E5 or E10 fuel?

Since September 2021, regular unleaded in the UK (apart from Northern Ireland) has been diluted down by 10% with an alcohol called ethanol. This is a standard known as E10. From 2019 to 2021, petrol had a 5% ethanol mix called E5. Northern Ireland will move from E5 to E10 from November 2022, although it’s been widely available there for the last year anyway. The EU also has E10 as its standard for regular unleaded petrol.

Premium unleaded, on the other hand, still only contains 5% ethanol (E5) and this will not change for the forseeable future. Is this important? That may depend on your car.

Adding ethanol to unleaded petrol is aimed at reducing CO2 emissions from petrol cars. Ethanol produces less CO2 than regular petrol so adding 5% and then 10% ethanol to the mix should help to reduce Europe’s overall CO2 emissions. However, some drivers have reported an increase in fuel consumption from the new E10 unleaded petrols.

Increasing ethanol levels has also caused other complications as well. Ethanol absorbs water from the atmosphere, which can lead to condensation in the fuel system and tank and cause corrosion. It’s also a solvent that is corrosive if exposed to materials like rubber, plastic and fibreglass. If you drive a modern car, that shouldn’t a problem. But if you drive an older car, you might have some issues.

Which cars should use premium unleaded?

Any petrol-engined car can run on premium unleaded petrol, but most cars don’t need it. Most normal cars are designed to use regular E10 unleaded petrol and using premium unleaded is unlikely to result in any performance improvement, although you may see a small improvement in fuel economy.

However, manufacturers of performance cars, like Porsche or BMW M Sport models, advise customers to use premium fuel in their vehicles. This is both to maximise performance and to help maintain the condition of the engine.

Habitually using regular unleaded fuel in engines designed for premium unleaded can cause long-term engine damage as the fuel will not ignite as easily under pressure. The odd tankful of regular petrol now and again won’t be a problem – which means you don’t need to worry if you pull up to a service station and they don’t have any premium unleaded available – but if your car is designed to run on premium unleaded then you shouldn’t continually run it on regular unleaded.

The suitable fuel for your vehicle can be found on the fuel cap, inside the fuel filler door or in the car handbook. All vehicles manufactured from 2019 must have the appropriate fuel type for the vehicle on or near the fuel filler. 

Vehicles built before 2002, and particularly classic cars, use materials in their fuel systems that may not be able to withstand the corrosive nature of E10. This can force some owners to use premium fuels as these still have a 5% ethanol mix.

All cars built after 2011 are compatible with E10. If you have an older car, check if it needs E5 by visiting the government fuel checker site. For more information on older vehicles and E10, read our guide

How much more expensive is premium unleaded petrol?

On average, premium unleaded is around 10p/litre more expensive than regular unleaded. By nature, premium unleaded is more expensive to produce but the price can vary depending on location and is influenced by regular fuel prices. 

To fully feel the effects of premium fuel on your vehicle, it’s advised you fill up the tank at least three times to establish whether premium fuel improves fuel economy or performance for your car and driving style. If you don’t see a noticeable difference, you may as well stick to regular unleaded and save money at the pumps. 

If there is a noticeable difference you need to decide if the extra 10p/litre is worth it for better performance or fuel economy. 

Can you mix regular unleaded and premium unleaded? 

Yes, certainly. If your tank is not empty, you can safely mix premium unleaded and unleaded petrol. Mixing the two will average out the octane rating, so it won’t lead to any damage but it will decrease the full potential of the premium unleaded fuel. 

How does premium unleaded petrol compare to adding booster additives?

Fuel additives from brands like Redex claim to do something similar to premium unleaded and improve performance and fuel economy. For high performance cars, booster additives are unlikely to be needed if the car is fueled with premium unleaded. For standard cars running regular unleaded, using a bottle of additives two or three times a year could help to clean the engine and help it to run more efficiently but prolonged use is not necessary. 

The cost of booster additives can vary from £5 to over £20 so it can work out more expensive to use additives rather than premium fuel. Like premium fuel, the best way to find out what works best for you and your car is to try it and see if there’s any noticeable difference. 

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Trinity Francis
Trinity Francishttps://www.trinitygfrancis.com/
Freelance automotive journalist and motoring writer focusing on all aspects of automotive content, with particular attention to emerging trends, industry innovations, tech and consumer advice.