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Petrol vs diesel

Should I get a petrol or a diesel car?

There are many differences between petrol and diesel cars – but the choice you make could end up saving you money, even on your insurance

By Kevin Pratt

Published: 01 October 2019

girl relaxing in car passenger seat

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The price of petrol vs diesel

Diesel cars tend to be more expensive than petrol: a petrol car is usually between £1,000 and £2,500 cheaper than an equivalent model of diesel car. While petrol cars are cheaper than diesel, this difference will be more or less significant depending on the overall cost of the car. If you’re buying a more expensive vehicle, the extra cost of a diesel engine might be balanced out by savings elsewhere.

In the past, diesel cars have held on to their value for longer than petrol cars, as diesel engines usually last longer. This means that if you think you might want to sell your car a few years down the line, it’s possible you’ll get a much better resale price for a diesel than a petrol model.

However, this is changing. Many new restrictions on diesel engine cars – which are worse for the environment – are coming into effect, and the longevity of their value is no longer certain.

Fuel economy

Diesel fuel is significantly more expensive than petrol at the pump – but diesel cars are also more fuel efficient. This means it’s cheaper to drive a diesel car in the long run, despite the up-front costs.

According to MoneySuperMarket research, the average motorist spends more than £100,000 on fuel in their lifetimes, so this could be an opportunity to make major savings.

However, the savings you make with diesel fuel might not be enough to cancel out the higher cost of a diesel-engine car. Many diesel cars won’t become cheaper than their petrol equivalent until you’ve driven them for five or six years – or up to 16 years for a VW Golf.

Driving a diesel car may still lead to savings if you’re planning to keep your car for a while, or if you frequently drive on motorways, where there’s a bigger difference in fuel economy.


The popularity of diesel vs petrol carsAccording to Department for Transport figures

Petrol vs diesel car insurance costs

When choosing between a petrol and diesel car, you not only need to take into consideration the mileage and fuel costs, but also the cost of insurance.

Because diesel cars are a little more expensive, it costs a little more to insure them. Insurers are pricing in the extra expense if your car is stolen, and the fact that parts and repairs will cost slightly more.

Vehicle taxes and charges

Laws on vehicle taxes for diesel and petrol engine cars have changed. Before 2017, vehicle taxes were calculated based on CO2 emissions, and diesel cars – which produce less CO2 – were taxed at a lower rate. Since 2017, both petrol and diesel vehicles are taxed at a standard rate of £140 per year after their first year.

This means that after the first year, you no longer pay lower taxes on a diesel than a petrol car. However, this only applies for cars registered on or after 1 April 2017. If your car was registered before then, you will still pay taxes at the old rate (adjusted in line with the Retail Price Index).

Diesel cars also face new restrictions and charges in some areas of the country.

Since 2019, London’s Ultra-Low Emission Zone has required all motorists in central London to meet the Euro 4 emissions standards or pay a £12.50 charge. Most petrol cars meet this standard, but few diesel cars registered before 2015 meet Euro 4 requirements.

The ULEZ, as it is known, will expand to include much of the city by 2021. Similar charges may soon be introduced in cities including Birmingham and Glasgow.

Some local authorities are introducing other charges for diesel cars. For instance, the London borough of Islington has imposed a £2-per-hour surcharge on short-stay parking for most diesel cars.

Are diesel cars more polluting than petrol?

Diesel cars produce less CO2 overall and are slightly better for climate change – but they also emit far more particulates which are toxic to humans, making them worse for use in cities.

Diesel engines are more fuel efficient and for many years were widely held to be a greener alternative to petrol, so the government introduced incentives to encourage people to buy diesel cars.

New information has complicated this picture: they produce an average of 11.5 times more nitrogen oxide than petrol cars. They also produce more particulates – microscopic pieces of soot left over from combustion, which are a major health hazard.

However, modern diesel cars are fitted with particulate filters to reduce these emissions, and manufacturers are beginning to claim that their new models are again cleaner than some petrol cars.

Other options: hybrid and electric cars

Hybrid and electric cars are increasingly popular alternatives to diesel and petrol vehicles. These cars are still often more expensive, but they are taxed at a significantly lower rate and are exempt from things like the London congestion charge. They are also much better for the environment.

By 2040, sales of new diesel and petrol cars will be banned, and all new cars will be required to have hybrid or electric engines.

Compare car insurance quotes

The best way to save money on your car insurance, whether it’s for a diesel or a petrol car, is to compare quotes with MoneySuperMarket.

Comparing car insurance only takes a few minutes and you could save hundreds of pounds on your premium. Get your journey started today and find the correct policy for you.