What’s the difference between petrol and diesel?

Lesson Type
Last updated: 10 Jul 2020

Whilst you’re learning to drive, you probably won’t give much thought to whether your driving instructor’s car has a petrol or diesel engine, but, when it comes to buying your own car, it’s something which you’ll need to take into account.

The differences between petrol and diesel might not be a topic at the forefront of your mind, but it’s important to choose the right car for you. Making the wrong choice could cost you financially, as insurance premiums and petrol consumption vary depending on the car you buy.

How do petrol and diesel engines differ?

Both petrol and diesel engines are internal combustion engines. This means that fuel is combined with an oxidiser in a small enclosed space, in turn producing enough energy to power your vehicle.

The difference between petrol and diesel is found in the way that the combustion occurs. Whilst a petrol engine combines fuel with air before being ignited by spark plugs, in a diesel engine the air is compressed beforehand and then the fuel is injected.

Why are diesel cars so popular amongst consumers?

The mechanical side of things probably won’t be something you’ll be particularly concerned about when choosing your first car. How, however, the difference between the two will effect you as a new driver is something which you need to consider.

Diesel cars, over the past few years, have become more popular amongst consumers, despite the fact that diesel is more expensive. This is largely due to the fact that diesel is a more efficient option, meaning you get more miles to the gallon.

Having said that, the popularity of diesel cars is reflected in the price. Diesel vehicles are often more expensive that petrol cars, not only because of their popularity, but also because of the fact that they require a stronger build. The explosions which occur in the diesel engine’s cylinders are much more violent than in a petrol equivalent, and, therefore, the engine must be heavier.

Low fuel consumption equals low tax

Because diesel engines allow you to cover more miles per gallon, diesel cars are often much more eco-friendly options than their petrol counterparts. Not only does this mean you can have a relatively clear conscience over your carbon footprint, but you’re also likely to fit into a lower tax band.

Petrol cars are also available with low CO2 emissions, and, consequently, low or no tax rates. Ford’s EcoBoost technology, for example, combines a petrol engine with smart eco-technology in order to provide a vehicle which falls into tax bad A (£0).

The problem with this, though, is that smart eco-friendly technology comes at a price which many new drivers simply can’t afford after forking out for driving lessons and insurance!

Engine size

Engine size is also something which you’ll need to take into account. Whether a car is petrol or diesel, you’ll need think about the engine size because this will effect the price of your car insurance.

As a new driver, you will want to reduce your car insurance premium in any way you can, and making sure you choose the right engine size is one of the most important factors. Car insurance is separated into 50 groups, with group 50 including the most expensive and powerful vehicles.

The most appropriate and most affordable cars for new drivers will fit into groups 1 to 3. These include the Vauxhall Corsa, Ford Ka, Skoda Fabia and the Volkswagen Polo, amongst other small vehicles.

Deciding between petrol and diesel

There are numerous factors to consider before deciding whether you’re going to buy a diesel or petrol car. You’ll need to think about how far you’ll be driving and whether the advantages of owning an efficient diesel outweigh the higher fuel costs and higher market value of a diesel car.

Petrol cars tend to be cheaper to buy, and, therefore, remain a favourite amongst young drivers, but high tax rates can be a downside.

Whichever car you decide to buy, make sure you do your research before handing any cash over. Look in the vehicle’s manual to find out how fuel efficient the car is and make sure you shop around for some insurance quotes before buying.