Petrol
‘RON’ octane rating
Before we explain the various types of petrol fuel, it’s important to understand what the ‘RON’ rating means. You would most likely of seen numbers on or above petrol pumps at fuel stations with numbers like ‘95/97/98 RON’. These refer to the octane rating of the fuel, which is a measure of how easily the fuel will ignite within the car’s engine – the higher the octane rating is, the harder it is for the fuel to ignite as it needs greater compression.
This may make you wonder why higher octane fuels are offered, but these fuels burn much hotter, meaning they can burn more efficiently and perform more optimally in higher-performance car engines.
Premium Unleaded (95 RON)
Don’t be fooled by its ‘Premium’ name tag, Premium Unleaded is actually the most commonly-used petrol across the UK, and is a suitable choice for almost all petrol engines.
Super Unleaded (97/98 RON)
Less commonly-used across the UK, but still available at most fuel stations is Super Unleaded. Featuring a higher-octane rating (97/98 RON), it is more suited to higher-performance cars that require it and benefit from using it, although it is still perfectly fine to use for most petrol vehicles.
Premium fuels such as Shell V-Power can provide even higher octane ratings (99 in this case), and claim to provide additional benefits like reducing engine friction, cleaning fuel system components and providing more power.
Is petrol the choice for you?
If it’s shorter journeys you normally do, then a petrol engine may be a more suitable choice than a diesel alternative. Most diesel engines are now fitted with a Diesel Particulate Filter which needs regular long journeys to avoid any clogging.
Check your car’s manual if you’re unsure what fuel to put in your petrol vehicle, although unless your car is a high performance model, 95 RON is almost always a suitable choice.
Diesel
‘Cetane’ rating
A cetane rating or cetane number (CN) is the rating given to diesel fuel to determine its combustion quality – this refers to the fuel’s delay of ignition time.
Most diesel vehicles use fuel with a rating between 45 and 55, and the higher the cetane rating is, the easier and more efficiently it will ignite and burn.
City diesel
You’ll often find that there is only one type of diesel at a fuel station, and this should be fine to use in any current diesel car or van.
Premium diesel
Some fuel stations will offer a higher-cetane diesel alternative under the name ‘Premium diesel’. Similar to higher-performance petrol fuels, this premium diesel fuel burns more efficiently, whilst also lubricating and cleaning the engine.
Is diesel the choice for you?
If you travel long distances at a time, use the motorway often or need to tow something, diesel engines are the choice to go for over a petrol alternative.
Diesel engines are generally more efficient too, offering better miles per gallon (mpg) and more torque, although may be more expensive upfront.
Hybrid
A hybrid vehicle uses two types of power source. Most hybrid cars consist of a petrol engine as well as an electric motor powered by a battery, although there are also diesel hybrid variants available.
There are two common forms of hybrid vehicles:
Mild Hybrid – petrol or diesel engine matched with an electric motor powered through a battery which self-charges through braking and other methods.
Plug-in Hybrid Electric Vehicle (PHEV) - petrol or diesel engine matched with an electric motor powered through a rechargeable plug-in battery.
Mild hybrid engines provide better fuel efficiency compared to a petrol or diesel engine by offering electrically assisted power at slower speeds, and there’s no need plug in as the battery recuperates energy from the engine and brakes.
PHEVs offer even better fuel efficiency by providing more electrically assisted power and a pure-electric range for short journeys, meaning you don’t even need to use the combustion engine on some occasions. You can then recharge the battery at home by plugging it into a wall box or traditional 3-pin socket.
Is hybrid the choice for you?
Hybrid vehicles are a great step to take if you’re not ready for a fully-electric vehicle but have efficiency at the top of your list of priorities.
It’s important to consider each hybrid option you have, and understand that hybrid vehicles are more expensive than their petrol and diesel alternatives.
Electric
An electric vehicle uses a motor that is powered by a rechargeable plug-in battery. The key benefit of this is that there is no combustion engine, meaning no need for forecourt fuel and no emissions.
As with PHEVs, you can charge your car from the comfort of your own home, or there is an ever-expanding list of plug-in points across the UK.
Is electric the choice for you?
Electric vehicles are a fantastic choice if you regularly commute on short the moderate journeys, and are happy to pay the small premium that comes with purchasing an electric car. While they can perform long journeys, it’s important to consider that you may have to recharge the battery on particularly long trips.
electric & hybrid vehicles