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Petrol or diesel? It’s a question car buyers have grappled with for decades. With each type of fuel offering different benefits and pitfalls, it can be hard to pick the one most suited to your lifestyle and driving habits. But fear not, because we’re here to help with our no-nonsense guide to common car fuel.
Weighing up the pros and cons of petrol and diesel, and taking a look at how they’re made, our guide is here to help you make the right choice when it comes to your next car. Use the links below to navigate or read on for the complete guide.
Petrol is the most common type of car fuel in the UK, with around 18.5 million petrol-powered cars on Britain’s roads. It’s one of the oldest types of fuel used in cars, with the patent for petrol being filed in the US in 1895.
Petrol comes from crude oil, which itself is hauled up from oil fields below the Earth’s surface. This oil is then refined through a process of heat and pressure, so that it can acquire the explosive properties needed to fire in an engine.
It’s impressive how petrol is made and then transported to your local fuel station. When crude oil is heated, it generates petrol vapours which rise to the top of the tank. This is then siphoned, stored and transported – pretty clever, right?
Not sure whether to buy a petrol or diesel car? Take a look at the pros and cons of petrol below.
Pros
• Affordable at the pumps
• More environmentally friendly than diesel
• Great for those who do most of their driving in town
• Superb range of engines, ranging from small to high-performance
• Simple maintenance
Cons
• Less efficient than diesel over long distances
• Some petrol engines are low-powered, with minimal torque on fast roads
• The lifespan of most petrol engines is around 150,000 miles – a diesel will do more
Ever wondered what the difference between unleaded and super unleaded is? And why one costs a few pence more per litre than the other? Let us fill you in.
Super unleaded is considered a high-performance variant of standard unleaded petrol. That’s because it has a higher-octane rating, usually of around 99 RON or higher. Generally, the higher the RON number, the greater the engine performance and the lower the consumption.
Standard unleaded petrol has an octane rating of around 97 RON, so the difference between the two is very slight. That’s why we wouldn’t really recommend paying more for super unleaded, unless you drive a classic car or high-end sports car that requires a performance fuel.
Lots of cars run on petrol, from city cars to sports cars, with the fuel being perfect for a wide range of engines. No other fuel type is as compatible with so many different engine capacities, making petrol a sound choice whether you want a fuel-efficient supermini, like a Ford Fiesta, or a high-performance saloon, like the turbocharged BMW M3.
Hybrid engines come in either petrol or diesel variants, consisting of a duel powertrain that combines a petrol or diesel engine with an electric motor. The engine and the motor work together to power the car while using a lower volume of fossil fuel than traditional engines.
A petrol hybrid can come in three different types: parallel hybrid, range-extender hybrid and plug-in hybrid.
A petrol parallel hybrid uses the electric motor from standstill up to roughly 15mph, when the petrol engine will kick in. Slightly more advanced, a plug-in petrol hybrid can be charged in the same way as an electric vehicle, giving it a larger range before the petrol engine has to take over from the electric motor.
Finally, the process is different for range-extender hybrids, which use the petrol engine to recharge the battery that powers the electric motor. In effect, the petrol engine powers the battery which powers the electric motor which powers the car. Range-extenders are not as common as parallel or plug-in hybrid models, so it’s less likely you’ll find one from your manufacturer of choice.
After petrol, diesel is the most widely used fuel in the UK, with an estimated 12.4 million diesel-powered cars on British roads. Like petrol, diesel has been around for decades, and was once billed as the ‘fuel of the future’ thanks to its impressive longevity and economy.
Diesel, like petrol, is produced when crude oil is heated. Diesel vapour is extracted from the same tank as petrol, though the oil needs to be heated for longer and at a higher temperature to attain diesel fuel.
When diesel first became available at fuel pumps, manufacturers touted it as a revolutionary product that would overtake petrol as the world’s go-to fuel. But this hasn’t quite worked out, as people came to realise that diesel was contributing more to air pollution than any other type of motor fuel.
If you’re unsure between buying a petrol or diesel car, we’ve made things easier with a quick look at the pros and cons of diesel engines:
Pros
• Excellent fuel economy and efficiency over long journeys
• High torque means diesel cars are excellent on high-speed roads, or for towing things like trailers and caravans
• Excellent acceleration from a standing start
• Durable engines which are capable of outlasting the equivalent petrol engine
Cons
• Diesel is more expensive to buy than petrol
• Diesel cars are also generally more expensive than the petrol equivalent
• Maintenance and upkeep can be complex and expensive, particularly with things like the DPF
• Diesel is much more harmful to the environment than petrol, meaning new tax hikes have been enforced in recent years
• Not as many makes and models available
Although there are a few smaller cars which offer a diesel variant, including the Ford Fiesta and Vauxhall Corsa, generally speaking, diesel is more often found on larger, high-powered vehicles. The whole purpose of diesel is to provide the perfect combination of torque, power and efficiency, so the fuel is ideal for saloons, 4X4s and SUVs that need a little extra power beneath the bonnet.
The three types of diesel hybrid engines work the same way as their petrol hybrid counterparts – all offer reduced fuel emissions compared to traditional engines. The higher price points of diesel cars and hybrid cars, however, can mean that diesel hybrid engines are reserved for only premium models.
As well as the fuel station mainstays of petrol and diesel, you may have noticed other pumps at your local garage, including biofuel and LPG Autogas. Let’s take a look at what these are and what they offer below.
The increasing popularity of electric vehicles means they’ll soon move from the alternative fuels section into the mainstream – especially when the ban on new petrol and diesel vehicles comes into effect. Registrations of new electric vehicles rose by 86% for the first six months of 2020 compared to the same period of 2019 – despite the impact of lockdown.
Purely electric engines need to be plugged into a charging station or a wall outlet to charge the battery that powers the car. For many people, fitting a wall outlet to their home is the best way to maintain an electric vehicle’s charge – plugging them in for a full charge overnight. To help keep a car’s charge on a long journey, there are charging stations all around the country, which are able to power up your vehicle to about 80% capacity in 30 minutes.
LPG Autogas is a new type of fuel that’s said to offer an alternative to petrol and diesel. Currently, no cars are built with an engine that’s specifically designed to run on this type of fuel, but there is the option to convert a standard petrol car to run on it.
According to DriveLPG, there are over 170,000 cars on UK roads which run on LPG Autogas, with the fuel offered at over 1,400 fuel stations across the country. LPG Autogas is very cheap to buy, although the low price is offset by poor performance and efficiency.
Biofuel is a new form of fuel that’s still in the development phase. Currently, biofuel is added to petrol and diesel to make these fuels more efficient and environmentally friendly, but there are plans to make it more readily available as manufacturers start building cars which run on it.
Biofuel is made from living matter, specifically biomass, that is refined and turned into a usable fuel. It’s not yet clear in what sort of situations biofuel will be an efficient choice for drivers, but it should be a good choice for those who regularly drive in a congestion zone – with no charges to pay for biofuel-powered cars.
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