Should I buy a petrol or diesel car?

What’s the difference between diesel and petrol cars?

Petrol and diesel cars differ mainly in fuel economy, running costs, performance and emissions.

Diesel cars usually use less fuel on long journeys and are better suited to motorway driving. Petrol cars are often cheaper to buy, cheaper to repair and better for shorter trips around towns and cities.

Is it more expensive to buy a petrol or diesel car?

Diesel cars usually cost more to buy than similar petrol models.

They can also cost more to maintain because parts such as diesel particulate filters (DPFs) and AdBlue systems may need servicing or replacing over time.

Petrol cars are generally cheaper to buy and repair, especially if you mainly use your car for shorter journeys.

Electric vehicles (EVs) and hybrid cars still tend to cost more upfront than comparable petrol or diesel models, although running costs are often lower.

Which is cheaper, petrol or diesel fuel?

Diesel is usually more expensive per litre than petrol.

The current average UK price for diesel is 141.4p per litre, compared with 132.4p for petrol*.

But diesel cars often deliver better fuel economy, especially on long motorway journeys, which can help offset higher fuel prices.

Which is more expensive to run, petrol or diesel cars?

Petrol cars are often cheaper to run for drivers who mainly make short trips or lower annual mileage.

Diesel cars may work out cheaper for high-mileage drivers because they tend to use less fuel over long distances.

Running costs also depend on:

• Fuel prices
• Servicing and repairs
• Car insurance
• Vehicle tax
• Emissions charges

Why are diesels better for motorway driving?

Diesel cars are often better for motorway driving because they use fuel more efficiently at steady speeds.

They also tend to deliver stronger pulling power at lower speeds, which can make long-distance driving feel more effortless on long journeys.

Because diesel engines are designed for efficiency over distance, they usually achieve higher miles per gallon (MPG) than petrol cars on motorways.

Diesel vs petrol: what’s worse for the environment?

Both petrol and diesel cars produce harmful emissions.

Diesel cars generally produce less carbon dioxide (CO₂) per mile than petrol cars, but they emit higher levels of nitrogen oxides (NOx), which are linked to air pollution.

Older diesel cars are more likely to face restrictions or charges in low-emission zones. Newer diesel models are cleaner than older versions, partly because technologies such as AdBlue and diesel particulate filters (DPFs) help reduce harmful emissions.

What environmental restrictions are there for driving in London and other cities?

Many UK cities now charge drivers of higher-emission vehicles through clean air zones (CAZ) or low-emission zones such as London’s Ultra Low Emission Zone (ULEZ).

Older diesel cars are more likely to be affected than newer models.

In many cases, diesel cars registered after September 2015 meet current emissions standards. Older models may face daily charges if they do not comply.

Driving a non-compliant vehicle in London’s ULEZ currently costs £12.50 per day.

Diesel vs petrol: what costs more to insure?

When it comes to car insurance, various factors beyond the fuel type of your vehicle determine what you pay. Personal information and circumstances such as your age, location, annual mileage, driving history and no-claims bonus all help calculate the premiums you're quoted.

So much more than the fuel type of your car is used to calculate your insurance premiums. However, diesel cars can cost slightly more to insure compared to petrol cars with similar specifications. This can be attributed to higher initial purchase prices and complex emission systems that can cost more to repair or replace.

How are petrol and diesel cars taxed?

If you plan on driving your car, you'll need to pay VED, or car tax, as it's more commonly known. It's a legal requirement, so driving without taxing your car can result in penalties ranging from fines to clamping if you're caught. Doing so can also invalidate your car insurance policy, and any potential claim may be rejected.

Put simply, all cars are taxed based on the emissions they produce, engine size and the year they were registered:

• Cars registered before 1 March 2001 are taxed on the size of the engine opposed to emissions.
• Cars that are registered between 1 March 2001 and 1 April 2017 are taxed on CO₂ emissions and placed into bands.
• A car registered on or after 1 April 2017 pays a standard tax rate. However, new cars are taxed according to emissions for the first year of registration, before moving to the standard rate.

Diesel cars in particular may pay a higher rate if they do not meet the Real Driving Emissions 2 (RDE2) standard for nitrogen oxide emissions.

Do diesel and petrol cars have a future?

In the short to medium term, yes. But the picture begins to muddy if we're looking at the longer-term future of diesel and petrol cars. That's because the UK government is introducing a ban on the sale of new petrol and diesel cars in 2030. In addition, the sale of new hybrid cars will also be prohibited in 2035.

The plans are part of a wider effort by the UK government to cut carbon emissions to achieve a net zero status by 2050. Essential to this is the phasing out of diesel, petrol and hybrid cars.

So, if you're asking, 'What happens to my diesel or petrol car?', here's what you need to know:

• The introduction of these bans only relates to the sale of new diesel, petrol and hybrid cars
• If your car falls under one of these fuel types, you'll still be able to drive it after the bans are enforced
• You'll also still be able to buy diesel and petrol cars once the law is in effect, as it only relates to the sale of new cars
• However, it remains to be seen as to whether the UK government plans to expand existing low-emission zones or create new zones in the future

So, if you're planning on buying a new diesel or petrol car, you'll have to do so before 2030. After this point, only second-hand cars will be available in these fuel types, before being gradually phased out over time.