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Diesel vs petrol: the pros and cons

Both diesel and petrol cars have come a long way in the last few years, with the differences between the two narrowing substantially. If you’re considering whether to switch from petrol to diesel or vice versa, this guide is for you. There are lots of misconceptions about diesel and petrol cars so we’re going to try and set the record straight, by listing the pros and cons of each. 

Pros of diesel cars

  • Diesel engines are more efficient. They can use up to 30% less fuel.[1]
  • They have lower CO2 emissions by 20%[2] so are often in a lower tax band. This means that you’ll pay less in car tax  in the first year, but then the standard £140 a year will apply.[3]
  • They're more powerful when towing a caravan or trailer.
  • Diesel engines usually have a longer life span.
  • Diesel cars depreciate at a slower rate. 

Cons of diesel cars

  • Diesel cars tend to be more expensive to buy than similar petrol models.
  • Diesel fuel usually costs more.
  • Servicing can be more expensive, although you don’t need to do it as often.
  • Insurance can be 10-15% higher. [4]
  • Diesel cars produce a lot more NO2.
  • Tiny particles in diesel can cause asthma flareups. [5]
  • Diesel engines can be slightly noisier.
  • If you don’t drive on motorways regularly your diesel particulate filter (DPF) could get clogged up and this can be expensive to put right.

Pros of petrol cars

  • Petrol cars tend to be cheaper to buy that similar diesel models.
  • Petrol fuel is usually cheaper.
  • Petrol engines can be slightly quieter.
  • Repair costs are typically lower.

Cons of petrol cars

  • Petrol engines are less efficient so use more fuel. 
  • Higher CO2 emissions by 20% so you have to pay more in car tax in the first year, but then the standard £140 a year will apply. [6]
  • They tend to depreciate faster.

Which wins?

There is no clear-cut answer to this question. For some people a diesel car is the best option, whereas for others, petrol works out better. Experts say that unless drivers do 10,000 miles a year in a used car or 6,000 miles[7] a year in a new car, a diesel car won’t work out cheaper. So, if your mileage is lower than these figures or you’re only planning on keeping your car for a couple of years, you might be better opting for a petrol car. 

Whichever you choose, diesel or petrol, it’s always worth shopping around for your car insurance to get the best deal. Insurers consider a number of factors when deciding how much you should pay for your premium. They look at how much it would cost to replace your car if it was written off and how much it costs to repair. Due to diesel cars being more expensive to buy than their petrol counterparts, this can mean that you have to pay more for your insurance. 

[1] http://www.express.co.uk/life-style/cars/565171/petrol-diesel-car-engine
[2] https://www.moneyadviceservice.org.uk/en/articles/choosing-between-petrol-and-diesel-power#petrol-versus-diesel-cars
[3] https://www.which.co.uk/reviews/new-and-used-cars/article/petrol-vs-diesel-cars-in-2017-which-is-better
[4] https://www.moneyexpert.com/car-insurance/petrol-vs-diesel-cars/
[5] http://www3.imperial.ac.uk/newsandeventspggrp/imperialcollege/newssummary/news_22-5-2017-10-31-19
[6] https://www.which.co.uk/reviews/new-and-used-cars/article/petrol-vs-diesel-cars-in-2017-which-is-better
[7] http://www.thisismoney.co.uk/money/cars/article-2130561/Diesel-vs-petrol-Used-diesel-car-cheaper-10-000-miles.html