A simples guide

Petrol vs diesel cars

When it comes to buying a new car, there are lots of things to think about – and one of the more fundamental is whether your car will be petrol or diesel. But diesel has had a bad rap recently, so is it really time to ditch it or are there still a few more miles left in the tank?

Which is better, petrol or diesel?

It would be easy to simply write off diesel, but it’s important to consider the context. Depending on where you drive and how many miles you do, diesel is still a sound option.

Some cars are traditionally diesel, such as 4x4s – diesels tend to be better at low torque, meaning you can tow more efficiently and be quicker off the mark. Most other car models are available in petrol or diesel options. And let’s not forget the rise of the AFV – or alternative fuel vehicles – which saw a 46% increase in new registrations in 2017 compared to the previous year.

A diesel car is a bit like a marathon runner – they’re fuel efficient on long journeys and will go further; what they don’t like is stop-start traffic or clogged-up urban roads. Diesels are in their element on motorways and are generally the better option if you’re driving more than 12,000 miles a year. Petrol cars, on the other hand, are more like fun runners – they use up fuel more quickly and are better for shorter journeys and nipping to the shops and back.

Bear in mind, though, that diesel cars tend to be more expensive than their petrol counterparts and the cost of diesel fuel can be pricier than petrol. Nevertheless, if you drive more than 12,000 miles a year, you could recoup around £1,000 in a year or two thanks to its efficiency.

When it comes to resale, diesels traditionally hold their value better than petrol cars (around 10% more). But only time will tell whether this will still be the case in the light of clean air zones and ‘toxin taxes’ on diesels.

But aren’t diesels really bad for the environment?

Newer diesel cars aren’t necessarily the social pariahs that they’re made out to be. Not only are they more fuel efficient but, on average, they emit 20% less carbon dioxide (CO2) than petrol cars.

Historically, CO2 has been the focal point when it comes to emissions. However, air pollution levels in some cities have gone beyond agreed European Commission limits, so the focus has shifted to address other polluting emissions, such as nitrogen oxide (NOx). It’s this focus on other toxins that has sparked the recent bad press.

By law, diesel cars need a diesel particulate filter (DPF) to catch as many emission nasties as possible. The DPF is self-cleaning but in order for it to do so, your car needs to be run for longish periods at high speeds. If the filter doesn’t get cleared and becomes blocked, it can be very expensive to repair.

But it’s not just DPFs that are helping smarten up diesel’s act. Diesel tech is constantly improving – since September 2015, engines have never been cleaner. New diesel cars have to comply with what’s known as the ‘Euro 6 regulation’, which means that diesels can’t emit any more than 0.08g/km of NOx. So, together with DPFs and compliance with Euro 6 standards, new diesels are ditching the dirty tag and are scrubbing up none too shabbily.

What about car tax?

New car tax rules – or vehicle excise duty (VED) – came into effect in April this year. If you’re buying a brand-new car, the cost of taxing it for the first year is based on the amount of CO2 it emits. As petrol cars produce more CO2 than diesels, you could face a higher rate of VED initially. 

And the cost of car insurance?

When it comes to insurance, it’s not so clear cut. The cost of your premium depends on a multitude of factors and it’s not just about the type of car you have. When it comes to totting up the cost of your car cover, insurance providers consider things like:

  • Your age
  • Where you live
  • How long you’ve been driving
  • How many miles you drive each year
  • Whether you’ve got any driving convictions
  • Whether you have a no claims bonus (and if so, how many years’ worth)

When it comes to assessing your car, its age, value, security and any modifications are all taken into account. Your car’s insurance group and the cost of repair and replacement parts will also be considered. And seeing as many newer diesels have fancy filters and emission-busting systems, diesel cars can be more expensive and costlier to repair than their petrol counterparts, which may mean higher insurance costs.

Ultimately, premiums are dependent on a raft of different things and while your choice of fuel won’t necessarily have a direct impact on the cost of your car insurance, it may well have an influence.

How can I be confident about getting a good deal?

At the end of the day, it’s down to you and your circumstances as to whether a diesel or petrol car is the better option. While diesels have taken a bashing, few in the motor industry would dump diesel completely any time soon.

But whatever you choose, we’re pretty sure you’ll want the best value when it comes to your car insurance – and we can help with that. Half of our motor insurance customers could have saved £282.99, simply because they were savvy enough to use comparethemarket.com. So, what are you waiting for? Start comparing today.

** Based on online independent research by Consumer Intelligence during May 2017. 50% of consumers could achieve a saving of up to £282.99 on their motor insurance premium with comparethemarket.com

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