In the world of car ownership, there are plenty of decisions to be made. And while it might seem like a small detail compared to some of the bigger questions you’ll have as a car owner, picking between premium and regular fuel can feel like a big deal especially when prices in the UK seem to be ever-increasing.

Premium fuel will cost a lot more than cheaper fuels and is marketed with a whole host of benefits. But what exactly is the difference between premium fuel vs regular fuel? What about premium diesel vs regular diesel? And is the extra price justifiable in the UK, are premium fuels ever worth it? Read on to find out. 

Is premium diesel worth it?

For the most part, premium diesel is just marketing fluff, and their frequent use offers little tangible benefit to your car. So in this case, it’s not worth paying for premium diesel over regular in the UK. 

Premium diesel vs normal diesel

Unlike petrol engines, in diesel engines, fuel isn’t directly ignited to create power. A consequence of this is that fuel quality is unlikely to affect the engine or cause knocking in the same way it does for petrol engines. This means the octane number is not used as a measure of quality. 

Diesel fuels feature a cetane rating, which is a measure of the ignition properties. Whilst you may have already heard of an octane number, there’s a good chance you haven’t heard of a cetane number.  

It’s not advertised or displayed on premium fuel products because all diesel engines are designed to operate well at the cetane number of normal diesel. Increasing the cetane number has no noticeable effects on performance.  

Although different cetane numbers do exist, premium diesel typically doesn’t have a higher cetane number than standard diesel. It’s the presence of engine-cleaning additives that distinguish premium diesel from cheaper fuels.  

These fuels are heavily marketed, such as BP’s Ultimate Diesel with ‘Active technology’. It claims to use ‘millions of dirt-busting molecules’ to fight off the harmful effects of dirt in your engine.  

However, the reality is that all diesel is manufactured to a certain standard, and all diesel engines are designed to run well off this standard.  

It's worth saying that using premium diesel occasionally won’t hurt your engine, and may give you peace of mind over its condition. However, using premium diesel all the time is most likely a waste of money for most people.  

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Is premium fuel worth it?

For most people with regular cars, paying for premium fuel is not worth it. If you drive a normal petrol or diesel car, splurging on premium fuels will offer you very little benefit. If you make sure to get your car regularly checked and serviced, you should have no problems with engine deposits; and there are no real performance benefits from premium petrol. 

But if you drive a high-performance petrol car, paying for premium petrol is vital. You’ll protect your engine from damage and ensure it runs as it was designed to.  

How much more expensive is premium petrol?

Typically, premium fuels will cost around 10p more per litre than their regular alternatives (although this can vary significantly and may further increase with rising fuel costs). For a normal car, this equates to £5 more per tank. If you use your car every day and fill up frequently this will eventually add up. 

Premium petrol vs regular petrol. 

The majority of petrol cars are designed to run perfectly well on regular petrol and will experience no discernible benefit from using higher octane premium petrol. 

Octane number is the measure of a fuel’s antiknock properties. A higher-octane number means the fuel is more likely to resist engine knocking and is suited for higher-performance engines.  

A difference in octane number is the key distinguishing factor between premium and regular petrol. Regular petrol is typically rated at an octane number of 95, and premium petrol is rated at 98.  

Using a higher-octane fuel than recommended by your manufacturer isn’t likely to harm your vehicle in any way, although it’s difficult to justify given the higher costs and lack of benefit. 

As previously mentioned, there are certain high-performance petrol engines that require a higher-octane level fuel. This is because these engines typically operate under higher compression ratios, and thus are more prone to knocking.  

Remember, high-octane fuels have superior antiknock properties and thus premium petrol is required to ensure the safe and efficient operation of these engines.  

What is the best fuel for my car? 

There are a few ways to find out which type of fuel is best for your car. The easiest way is to read the information on the fuel filler door on your car. It’ll tell you which type of fuel you need to use and whether your manufacturer recommends high-octane variants. 

You can also check your car’s manual or use an online car checker. Most petrol stations offer a variety of standard and premium fuels, so they’ll be something for you. 

Do high-performance cars need premium fuel?  

Premium fuel isn’t required for most types of cars, but it is recommended for some high-performance vehicles. Cars with high-performance petrol engines typically require premium petrol to run properly. This is usually made clear by the manufacturer; all cars that are designed to run on premium fuel will have a label on their fuel filler door to indicate this.   

If you ignore this guidance and put cheaper fuel into your high-performance petrol engine, you’ll likely notice a reduction in your engine’s performance and efficiency. This might also result in damage to your engine due to excessive knocking.   

There is also premium diesel on offer, but there are no vehicles that require premium diesel to run well. Usually, the main difference between premium and regular diesel is the addition of additives.   

These are chemical substances designed to clean the engine, ensuring the engine can run as efficiently as possible.

The bottom line 

With a wide range of premium and regular fuel products, knowing what’s best for your car can be confusing. For the majority of petrol car owners, using premium petrol on a regular basis will likely result in no performance benefits, and it will cost you a significant amount more than using cheaper fuels.  

The only exceptions are high-performance petrol vehicles, where the use of high-octane premium fuels is essential. 

Whilst there’s a lot of marketing hype around premium diesel, the reality is that your car is designed to run on regular diesel. You’ll get no discernible benefits from splurging on premium diesel products, and it will most likely be a waste of money.