Premium fuel like super unleaded petrol costs more at the pump than standard fuel, but there are some benefits to using it. We talk about this and whether you can mix unleaded and super unleaded when you're at the pump.
What is premium fuel?
Often referred to as ‘super unleaded petrol’ or ‘high performance diesel’, premium fuels have a higher-octane rating than other fuels also offered at the pumps.
What is high octane fuel?
A high-octane fuel is usually harder to ignite because it requires greater compression to do so than lower octane fuels.
The higher the octane rating, the less likely the petrol is to explode under pressure.
High-performance engines typically compress their fuel more. By using higher octane fuel, you’re able to avoid unexpected explosions that might damage your engine.
Standard fuels typically have a 91-95 octane rating whereas premium or super fuels have a rating of around 98-99.
You can also buy premium fuel diesel vehicles too – these come with a higher cetane rating.
Whether you’re filling your tank with higher octane or cetane fuel, the usual reason for doing so is to increase efficiency and improve performance.
How do I know if premium fuel is suitable for my car?
Your car handbook should provide you with details on the recommended octane (or cetane) rating for your engine.
The information might also be included in the casing around your fuel cap.
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What is super unleaded fuel?
Super unleaded petrol is typically a higher-octane version of regular unleaded petrol.
This means it has a higher-octane rating. Ordinary unleaded usually has an octane rating of around 91 Research Octane Number (RON).
Super unleaded petrol usually has a rating between 97 RON and 99 RON.
The octane number is what you should focus on as the labels ‘Premium’, ‘Supreme’, ‘Super’ and ‘Ultra’ can be quite confusing and not always mean the same thing.
What brands of premium fuel are on the market?
There are several brands of high octane or high performance fuel available at UK petrol stations.
- BP offers Ultimate Unleaded and Ultimate Diesel
- Shell offers Shell V-Power
- Texaco has developed its Supreme Unleaded 97
- Total has Excellium Unleaded petrol
- In 2020 Esso launched its Synergy Supreme+ 99 fuel
Does my car require a certain fuel type?
All cars must use a specific fuel type, which might be unleaded E5 or E10 petrol, diesel, Liquefied Petroleum Gas (LPG) or increasingly these days, electric battery.
You should be able to find what fuel your car runs on in it’s manual. Or on the petrol cap.
Can you mix unleaded petrol and super unleaded petrol?
Mixing standard unleaded petrol with a ‘Supreme’ or ‘Ultimate’ unleaded premium fuel is unlikely to do your engine harm.
For example, if you mix super unleaded petrol with the standard petrol that’s already in your tank it shouldn’t affect your engine.
This should apply to premium and standard diesel too.
But make sure you’re putting the right type of fuel in your car. Those of us who’ve put diesel in a petrol car or petrol in a diesel car will testify that these fuel types don’t mix well!
Is premium fuel better for your car?
The producers of premium fuels insist that they provide noticeable benefits – notably that they remove dirt from the inside of the engine and help it to run smoothly.
Some cars run optimally on standard unleaded fuel, while others run more efficiently on higher octane fuels like super unleaded.
This is why it’s worth checking your car manufacturers’ handbook for guidance on fuel.
It should be perfectly fine to use a higher-octane fuel than the manufacturer recommends for your car – though it’s unlikely to offer any discernible benefit.
The only guarantee is that it costs more. However, using a lower-octane fuel than your car manufacturer recommends could result in engine damage over the long term.
If you own a high-performance car, the manufacturer might insist you use a premium fuel to ensure maximum driving performance and fuel efficiency.
How much does premium fuel cost?
You won’t be surprised to hear that premium fuel costs notably more than its regular alternative.
As of 14 June 2022, regular unleaded could cost you around 175p a litre and regular diesel could cost 183.1p per litre, on average.
This compares to premium fuels such as super unleaded petrol costing around 181.9p per litre and premium diesel costing around 188.7p. Visit our fuel price index for a more in depth breakdown of fuel prices.
In this instance, we’re talking about a price difference on unleaded fuel of 7p per litre compared to the premier fuel option. Fuel prices may vary depending on the provider and region.
The gap between regular and premium fuel options could be as much as 20p per litre or more as the price of fuel fluctuates so frequently. On a full tank of fuel, the price differential can really hit the pocket.
Is paying extra for premium fuel worth it?
Whether it's worth the extra cost is debatable. Certainly, for someone driving a small-to-medium sized engine, using premium fuel regularly is likely a waste of money.
It doesn't provide extra power or speed – it just costs you more at the pumps.
It’s true that some high-octane fuel have cleaning qualities. This could improve the efficiency of older engines that have run on regular unleaded for years.
With this in mind, a tank of high-octane petrol might be beneficial once in a while. The fact is that the vast majority of cars function perfectly well on 95-octane standard unleaded fuel.
However, a few high-performance sports cars benefit from using premium fuel – in terms of improved performance, engine protection and greater fuel efficiency.
If you think your car might benefit from high-octane fuel and the manufacturer suggests it as an option – try it out for yourself. If you can’t really see any improvement in fuel efficiency or performance, it’s probably fine to take the regular fuel option.
You can find out how much your journeys are costing you with our fuel cost calculator. You should be able to use this to work out the difference between premium and regular fuel too.
Should you fill your second-hand car with premium fuel?
This all depends on what type of second-hand car you have. There’s a big difference between a high-powered Porsche and a 1.2 litre Ford Fiesta!
If the Porsche has been filled regularly with premium fuel and drives like a dream – maybe there's a good argument for sticking with it.
Similarly, if you drive a less-powered vehicle you could flush through a few tanks full of premium fuel to clean out the engine.
How can I save on fuel?
Whether you’re using super unleaded petrol or premium diesel, you can still make the most of your fuel with our fuel efficiency tips:
- Make sure your tyres are inflated to the right pressure
- Remove any excess weight from your car
- Remove your roof box if you’re not using it
- Try to drive smoothly and avoid sudden stops and acceleration if you can