Most fuel stations in the UK offer “super” or “premium” unleaded petrol or diesel that they often claim improves the performance of your car and helps to protect your engine, all while improving your fuel consumption.
Such fuels can cost up to 10p more per litre than standard fuels, so the burning question is – are they worth the extra outlay?
So what is premium fuel?
Premium fuel is more expensive than standard fuel largely due to its higher Research Octane Number (RON). The benefits of this increased octane rating are supposed to include lower fuel consumption as well as better engine protection as well as performance. In the UK, the standard RON of unleaded fuel is 95, while super unleaded is around 98 RON. Some of the big petrol companies also sell a top-of-the-range fuel with 102 RON. The big fuel companies back the claims that a higher RON is better for your car.
Does premium fuel improve mileage?
The higher-octane rating in the premium fuels available should mean that the fuel works more efficiently, thus delivering more power to your car while burning less fuel.
Some drivers report a small increase in the number of miles they can drive before having to fill up again. However, others find that there is in fact little to no difference when compared to standard fuel. It may be that the number of miles that you get from your tank will depend on other factors such as how and where you drive, as well as what engine is in the car that you drive.
Does premium fuel improve performance?
Just as with the fuel consumption, the increase in performance that you can expect from premium fuels will largely depend on the type of car that you drive, the way you drive it and the nature of the journeys you take.
The premium fuels that have the higher-octane count will tend to benefit high-performance engines where the pressures and temperatures exerted on the fuel are far greater. It will boost the amount of available horsepower available and therefore improve performance.
Normal engines however do not come with the same compression ratios as turbo charges and supercharged engines found on performance cars. This means that a lot of the characteristics of the high-octane fuels are wasted on these engines.
So generally speaking, the drivers that will benefit from the premium fuels are the ones who drive performance cars – especially if they drive them hard on open roads.
People who just use their car for short trips such as running errands and weekly shopping trips are unlikely to see as many of the benefits of premium fuel.
Does premium fuel reduce engine wear and tear?
Higher-end fuels are thought to reduce the chances of engine-knock, which is where unburned fuel per-ignites inside the vehicle’s engine and damages interior components. The higher the Ron of a fuel, the more controlled manner the fuel will burn, therefore decreasing the chances of knocking.
Engine knocking is not something that is exclusive to performance cars, but it is something that occurs more often in such engines. Therefore, premium fuels are more likely to benefit cars with performance engines and higher compression ratios than the engine you will get on your bog-standard Fiesta for example.
As well as a higher Ron, premium fuels contain additives which help to keep your engine clean inside, meaning that it will last longer.