Is it worth paying more for premium fuels? Pros and cons of different fuel types

Julie Daniels
Insurance expert
5
minute read
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Last Updated 10 OCTOBER 2022

The cost of fuel has been a topic at the forefront of drivers’ minds in recent months. Earlier in 2022, we saw petrol prices reach unprecedented levels, which forced many car owners to think twice about their current driving habits.

Although fuel costs are higher than ever, garages still offer a choice between regular petrol and diesel and a premium or ‘super’ version. But should you be spending more to fill up your car?

Producers will claim the high-end variations offer many different benefits to both your driving experience and your car’s engine. But why specifically are these big-ticket fuels branded as the most premium options, and how does the everyday driver stand to benefit from using them? First, we need to understand what makes these fuels ‘superior’ in the first place.

How do we measure fuel quality?

The quality and performance of petrol is measured using an octane rating, commonly referred to as the Research Octane Number (RON). In theory, the higher the RON, the more efficient the fuel will be, since this number refers to the amount of pressure it can withstand before combusting. This means that higher RON fuels are less likely to ignite before needing to be used by your car, which ultimately improves its efficiency.

Fuels with low octane numbers are more compatible with diesel engines, since they aren’t being compressed in these vehicles. Instead, the quality of diesel is measured more on its cetane value. Cetane is naturally found in diesel, and is a highly flammable chemical compound, which ignites easily when compressed. Substances known as cetane improvers can be added into the diesel fuel blend to improve the cetane value and thus overall quality. This value typically ranges between 45 and 55 in different types around the world, and just with the RON of petrol, the most premium diesels will typically come with a higher value.

Unleaded versus super unleaded

According to government statistics, the majority of cars on Britain’s roads are petrol powered. At the end of 2021, just over 58% of registered cars in Great Britain ran on petrol, whilst around 36% were powered by diesel. This means that the majority of drivers are reaching for the unleaded pumps when filling up, but usually there will be two options at the forecourt. So, what’s the difference between the two common types of unleaded petrol, and does it matter which you choose?

Unleaded petrol is the most basic, and often cheapest, fuel found in our forecourts. Since September 2021, the default unleaded petrol stocked in UK petrol stations has been E10 fuel, which helps to reduce overall emissions. Every version of this fuel that’s sold across the country will have a RON of at least 95, but you may find unleaded petrol with a lower octane rating in other parts of Europe.

Meanwhile, super unleaded is the highest-quality petrol that’s widely available in UK petrol stations. Different brands have their own versions of super unleaded fuel, but this type will have a higher octane level than regular unleaded. This means that it’s better suited to performance cars, but can be used in just about any petrol engine. There are a range of different options available, including BP Ultimate petrol, Shell V-Power petrol and Total Excellium Unleaded.

To the average driver, the small increase in octane rating will make no tangible difference to their driving experience. So what factors should you consider when deciding which petrol is best for you, and which type comes out on top in these different areas? 

Pump price

One of the most important factors in many people’s minds when choosing which pump to grab is the price, and in this department, standard unleaded is the clear winner. In fact, the relatively low cost of unleaded compared to the other pumps is likely the primary reason most drivers continue to use this fuel.

In October 2022, super unleaded was 14p more expensive per litre than its lower-quality counterpart. And whilst prices are predicted to come down, the top-end version will remain at a higher price point. 

With the backdrop of rising living costs, this factor alone may be enough to convince many drivers to opt for standard unleaded.

Winner: Regular unleaded

Versatility

A major downside of regular unleaded is it can only be used in certain cars. This is because in high-performance engines, the lower octane rating can not only mean the standard version burns more inefficiently, but it can even cause engine damage in the long-run. 

Whereas the higher octane rating of super unleaded means it’s generally acceptable to use in any petrol-powered car. This fuel may not be as efficient in regular cars compared to performance vehicles, but it will provide some benefits, and certainly won’t do the engine any harm. 

If you're unsure which would be best for you, it’s unlikely that mixing the two types would cause any long-lasting damage to your vehicle. So if you usually top up with regular petrol, but want to see whether super unleaded performs better for you, you can always try it out. Just be sure to check your vehicle handbook before changing your fuel, to ensure it’s compatible with your engine.

Winner: Super unleaded

Performance

Super unleaded fuel is specifically designed to boost performance in high-end cars and engines. With a higher octane number, this fuel will ensure high-performance vehicles can run optimally, without causing harm to the engine. 

However, filling up a mid-range hatchback with super unleaded won’t suddenly transform it into a car primed for the Silverstone track. In fact, the average driver is unlikely to feel any noticeable difference at all in performance between the two fuels when driving a middle-of-the-range model. Whilst there are engine-cleaning properties to super unleaded fuels, which could prolong the lifespan of your car, any improvements in day-to-day performance will be very subtle.

Winner: Super unleaded (in high-performance cars)

Diesel versus supreme diesel

If you drive a diesel-powered vehicle, you may be wondering how all this relates to you. Well, diesel car drivers will also often have the option to top up with a higher grade fuel, though it is less commonly available than super unleaded.

Due to the way in which diesel engines work, using a fuel with a higher octane rating wouldn’t actually improve performance. Instead, the most premium diesels on the market will have a higher cetane value, and also contain additives which help to clean the engine. This ensures the car can continue operating at its optimal level for longer.

There are lots of popular varieties on the market, including Esso’s Synergy Supreme+ premium diesel, bp Ultimate Diesel and Shell V-Power Diesel.

Pump price

The cost of diesel is almost invariably the highest number on the price displays at petrol stations across the country. In the UK, both petrol and diesel are taxed at the same rate by the government, meaning that the reasoning behind the difference in price is primarily down to supply and production costs. But, it’s important to note that diesel engines are generally considered to be far more efficient than petrol alternatives, meaning that diesel has traditionally been the more economical option in the long term. 

When we compare the price of standard diesel with its premium counterpart, there is further disparity, with the latter attracting a higher price tag. And whilst you may be reluctant to pay a hefty premium on top of what is already a costly commodity, there are many benefits to using the high-end option on occasion.

Winner: Regular diesel

Performance and economy

Whilst a higher cetane value will result in better ignition quality, the main benefits of using supreme diesel come from its cleaning and lubricating properties – the additives will help to clean your car’s fuel system, to maintain optimal engine performance. Though you may initially be paying more for supreme diesel, the long-term cost benefits are double-edged. Not only will its cleaning properties help to reduce ongoing maintenance costs, but it will also maintain and even improve your car’s efficiency. 

However, the performance and economic benefits will vary from car to car. For instance, topping up a brand new diesel motor with the most high-end fuel on the market will offer very few benefits, since there won’t be any build up of soot or other dirt in the fuel system. But if you have bought a second-hand car that’s had years of wear and tear, using a supreme diesel to flush out the system will provide noticeable benefits, and help to keep it working properly. 

In this way, you don’t necessarily need to use the most expensive fuel every time you top up. Filling up with supreme diesel every once in a while will be enough to ensure you feel the benefits, whilst also getting the most for your money.

Winner: Supreme diesel

Potential alternatives

With the UK Government’s 2030 ban on the sale of new petrol and diesel cars looming over motorists' heads, many drivers are starting to consider what life after fossil fuel-powered cars may look like. Fortunately, whilst petrol and diesel cars remain popular, they’re no longer the only options available, and modern technologies are making it increasingly easier for drivers to use alternative fuels. 

Electric vehicles (EVs) are considered the most likely and viable alternative to petrol and diesel powered-cars, and the UK’s infrastructure is continuing to grow to support the rising demand for EVs. In July 2022, there were 32,011 public electric charging points in the UK. This marks an increase of over 7,600 public points in the 12 months from July 2021. Though these figures are encouraging, there is still a vast disparity between the concentration of public points in different regions of the country, and this will have to be addressed if electricity is to become a sustainable option for everyone. 

Hydrogen is another option that’s being explored by manufacturers and producers around the world. When used to power a car, hydrogen produces no tailpipe emissions, making it inherently cleaner than fossil fuels. However, there are currently many challenges associated with the use of hydrogen as a fuel source, including high production costs, distribution, and safety concerns. Despite these barriers, hydrogen remains a potential alternative, and could be used to power cars of the future. 

Deciding what’s right for you

Having discussed some of the advantages and disadvantages to using different types of fuel, hopefully you have all the information you need to make a more informed decision next time you need to top up your tank. 

If you’re looking for the best possible performance and efficiency from your car, then it’s best to follow the manufacturer's guidelines set out in your vehicle handbook. This will contain information around which fuel will perform best with your particular make and model. Ignoring this advice and using the wrong fuel could cause significant damage to your car’s engine, and lead to costly repairs further down the road.