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Petrol vs Diesel: The Basics

There was a time when diesel cars were the obvious choice thanks to better fuel economy and lower tax. But with growing concerns surrounding the impact of diesel engine emissions on the environment and people’s health in urban areas, coupled with petrol engines becoming more economical – the decision is no longer as clear cut.

We’ve created a straightforward guide for those who don’t speak in “torque” or “MPG” so that you can make an informed decision when choosing between a petrol or diesel car.

Purchase Price

As a result of the huge investments that manufacturers have made in the development of diesel engines in recent years, diesel cars can be on average €1,000 to €2,000 more expensive to purchase than petrol cars.

Running Costs

Generally speaking, if you cover mileage of over 18,000km a year and most of your driving is on motorways, a diesel car is more economical as diesel cars cost less to fill and you will make fewer trips to the fuel pump. If most of your journeys are local and you’re covering less than 18,000km a year, a petrol car will likely suit your needs better. Put simply, if you purchase a diesel car the amount that you save on fuel over the lifetime of ownership should make up for the higher purchase price.

When comparing the running costs of petrol versus diesel cars, tax and insurance should also be considered. Insurance tends to be slightly higher for diesel cars because of the increased value. Currently, diesel cars have cheaper motor tax than petrol cars but with mounting pressure to address the pollution concerns associated with diesel cars, motor tax for diesel cars may increase in the future.

Performance & Maintenance

Here’s where we delve a little into comparing the performance and maintenance of diesel versus petrol cars (not to worry though, we’ll still keep it as straightforward as possible). One unique feature for diesel cars is the diesel particulate filter, otherwise know as the DPF. In order to keep the filter unblocked, many owners’ handbooks advise running the engine at high speed, for example on a motorway. If you don’t regularly drive on motorways, you run the risk of blocking the cars DFP which can cost thousands to replace.

Maintenance costs are similar for a petrol and diesel car but it can be more expensive to repair a diesel car is anything serious goes wrong. With that being said, most newer diesel cars only require a service every 2 years or 30,000kms compared with petrol cars which need to be serviced once a year or every 15,000kms. We should also mention the obvious when talking about the performance of diesel versus petrol cars, which is that diesel engines offer a smoother driving experience. As a result, a diesel engine is best suited to larger cars such as SUV’s and 4×4’s.

The Future of Diesel

While covering the basics, it’s important to briefly acknowledge the future of diesel cars. As we’ve mentioned already, there are rising concerns over the effects that diesel emissions are having on the environment and on people’s health, particularly those in urban locations. In the short-term, this could potentially have an effect on motor tax prices and even fuel prices which in turn may cause fluctuations in the trade-in value of diesel cars.

When deciding on whether a petrol or diesel car will best suit your needs, your best bet is to weigh up the pros and the cons above according to how you use your car and use independent car reviews like those featured on the DoneDeal Motor Magazine to make sure your purchase is right for you.

Still not sure if petrol or diesel will suit your needs better? Here’s our quick guide:

Choose a diesel car if:

  1. You regularly drive on motorways

  2. You travel over 18,000kms per year

  3. You have the budget to cover additional insurance and maintenance costs

  4. You’re looking for a larger car like an SUV or 4×4

Choose a petrol car if:

  1. Most of your driving is local or within a city

  2. You are concerned about the future trade-in value of your car

  3. You are price sensitive when it comes to purchase price, insurance and maintenance costs

  4. You’re not concerned with engine power or performance


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