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Petrol vs diesel cars

When it comes to buying a car, one of the biggest considerations is diesel vs petrol. We weigh up the pros and cons of each to help you decide which fuel type will work best for you.

When it comes to buying a car, one of the biggest considerations is diesel vs petrol. We weigh up the pros and cons of each to help you decide which fuel type will work best for you.

Written by
Julie Daniels
Motor insurance comparison expert
Reviewed by
Rory Reid
Car and technology expert
Last Updated
2 AUGUST 2023
6 min read
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Which is better: a diesel or petrol car?

When comparing the merits of diesel and petrol, there’s a few things to think about, including your budget, mileage and where you drive your car.

Pros of diesel cars

Diesel cars have been much maligned in recent years, but they still offer a few advantages over petrol vehicles. These include:

  • Fuel efficiency
    Diesel engines are typically more fuel efficient than petrol engines, giving you far more miles to the gallon. This means they can cost you less to run over time.
  • Lower CO2 emissions
    Because diesel cars use less fuel than petrol cars to travel the same distance, they emit less CO2 overall. The problem is that they produce much more nitrous oxide (NO2), the small particulates that are extremely bad for lungs.
  • Cost-effectiveness for high mileage
    If you use the motorway frequently and clock up a lot of miles in a year, a diesel car has better fuel consumption, so is likely to be more economical.

    But it’s worth bearing in mind that the average mileage for drivers in England fell below 5,000 miles a year in 2022, so you may well find it isn’t worth the extra outlay.
  • Towing capability
    Diesels generally produce more torque – or pulling power – than petrol cars, which can mean they’re better at towing. However, your car’s make and model will also have a bearing on how much load it can carry.

Cons of diesel cars

Unfortunately, diesel cars come with a number of downsides too. These include:

  • Initial cost
    Diesel cars can be more expensive to buy than petrol cars, although how much you pay will depend on the car’s age, make and model. You’re likely to find you pay more for diesel fuel too.
  • Air pollution
    Diesel cars were initially welcomed for reducing carbon emissions. But they were found to produce higher levels of particulates – tiny bits of soot that enter the lungs and can lead to asthma attacks.

    According to government figures, air pollution causes between 28,000 and 36,000 deaths each year in the UK. Diesel cars are known to be a big part of the problem.
  • Restrictions/surcharges
    To combat air pollution, cities like London and Birmingham ban older diesel cars from central areas, or charge drivers for using them.

    For example, if your diesel car was registered before September 2015, you’ll probably have to pay a £12.50 charge to drive into London’s Ultra Low Emission Zone (ULEZ).

    Many local councils also charge more for parking diesel cars
  • Maintenance costs
    How much you pay to maintain and repair your car will depend on its age, make and model. However, as a general rule, diesel cars cost more to maintain than petrol cars.

Pros of petrol cars

There are advantages to buying a petrol car, including:

  • Lower initial cost
    Petrol cars can cost less to buy than diesels, but again this will largely depend on the age, make and model.
  • Better for short trips
    While diesel cars can be more economical on longer trips, petrol cars are better for short commutes or trips into town.
  • Noise and comfort
    Petrol cars tend to be quieter than diesel cars, as well as offering a smoother ride with fewer vibrations. Again, this will vary depending on your car’s make and model.
  • Less local air pollution
    Petrol cars don’t produce the same levels of NO2 as diesel cars, making them less polluting. However, they still cause unhealthy levels of CO2 emissions and are a major cause of climate change.

Cons of petrol cars

  • Lower fuel efficiency
    When it comes to fuel efficiency, diesel cars have the edge on petrol. If you’re looking for a car that does more miles to the gallon, you’re better off with diesel.
  • Higher CO2 emissions
    Petrol contains a lot of carbon and burning it creates CO2 emissions. According to the BBC, the average petrol car on the road in the UK produces the equivalent of 180g of CO2 every kilometre, while a diesel car produces 173g of CO2 per km.
  • Not ideal for towing
    Petrol cars don’t tend to be as good as diesel at carrying heavy loads. But, again, it depends on the model you drive. A Range Rover, for example, can tow up to 3,500kg.

Taxes: petrol vs diesel calculations

How much road tax you pay will depend on whether your car meets the Government’s Real Driving Emissions 2 (RDE2) standards. These set the maximum level of a car’s NO2 (nitrogen oxide) emissions.

When you register your vehicle, you’ll pay an upfront tax rate based on your car’s CO2 emissions. This covers you for 12 months and is more expensive for cars that don’t meet the RDE2 standard. Ask your car manufacturer for your vehicle’s base emissions.

You don’t currently have to pay road tax on electric cars. However, this will change in 2025.

Should I buy a diesel or petrol car?

Whether you should buy a diesel or petrol car will very much depend on your personal circumstances and needs.

However, it’s worth taking a long-term view. The Government is phasing out the sale of new diesel cars in the UK from 2030 and as of 2035, all new cars will need to be zero emission.

So a diesel or petrol car may suit you in the short term, but beyond that it’s worth thinking about alternative fuels.

Will having a diesel or petrol car affect my car insurance?

It’s hard to say whether your vehicle’s fuel type will affect your car insurance. How much you pay for your premium depends on a number of factors, not just the car you drive.

Insurance providers will also take into account your:

  • Age
  • Address
  • Driving experience
  • Mileage
  • Any driving convictions
  • No-claims bonus.

When it comes to assessing your car, other factors also affect how your car insurance is calculated. These include your car’s value, your home security and whether your car has any modifications.

Your insurance provider will also consider how much the car costs to repair, along with the price of replacement parts.

Many newer diesel cars have fancy filters and emission-busting systems, making them more expensive to repair than their petrol counterparts. This could lead to higher insurance premiums.

What about hybrids and electric cars?

While they tend to be more expensive to buy or lease, electric cars are far cheaper to run than either diesel or petrol cars. They’re also zero emission and bring you serious discounts on road tax, congestion charges and even parking.

Hybrids – sometimes known as plug-in electric hybrid vehicles (PHEVs) – let you drive on electricity for short distances, before reverting to petrol. They’re great for short commutes.

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Frequently asked questions

Are diesel or petrol cars better for the environment?

It’s complicated. Diesel cars cause more problems for human health, as they emit small particulates that damage the lungs. They do give off lower CO2 emissions though, which arguably makes them slightly less harmful to the environment.

Should I buy a second-hand diesel or petrol car?

It depends on the age of the car you’re buying and where you’ll be driving it. A pre-2015 diesel car is likely to cost you a lot when it comes to road tax and low-emission zone charges. But for that reason you might find a great deal.

Julie Daniels - motor insurance comparison expert

Julie is passionate about delivering a great customer experience and rewarding people for saving on their insurance through our loyalty and rewards programme. She’s spoken to the media, including outlets like Sky News and Capital FM, about car and home insurance, as well as our rewards scheme.

Learn more about Julie

Rory Reid - car and technology expert

Rory Reid is a car and technology expert. He serves as the main presenter on Auto Trader’s YouTube channel and was previously a host on BBC Top Gear and its sister show Extra Gear. He is also a presenter on Fifth Gear. Previously, he hosted Sky TV’s Gadget Geeks, CNET’s Car Tech channel, BBC Radio 5 Live’s Saturday Edition and on the YouTube channel Fast, Furious & Funny.

Learn more about Rory

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