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Should I buy a diesel car?

We look at the pros and cons of owning a diesel car, and whether it's worth buying a diesel car or if it’s time to sell up and convert to another type of fuel.

 A driver fills up their diesel car

Diesel cars have become significantly less popular over recent years due to drivers’ worries about rising costs, pollution and government policy.

A decade ago, diesel cars represented just over half the car market, but there’s since been a sharp decline. In fact, last year diesel models made up only 16% of new UK car sales.

The Volkswagen scandal of 2015 marked the beginning of the end for diesel cars. The German marque had dramatically under-represented the nitrogen oxide levels emitted by some of its diesel cars so it would meet US standards.

These gases have been linked to respiratory illnesses, including asthma and lung cancer.

Since the VW scandal came to light, diesel has received a lot of bad press. The concerns over nitrogen oxides have prompted governments and local authorities to target diesel cars with restrictions and higher costs.

In fact, many cities have made it clear that they just don’t want diesel cars which emit lots of harmful gases on their roads.

Should I buy a diesel car?

Whether it’s worth buying a diesel car these days partly comes down to how you plan to use it. If you’ll mainly be using the car for long journeys on the motorway, then a diesel could make sense.

However, if you’ll just be making short trips across town, perhaps for school runs or picking up your shopping, then buying a diesel car is unlikely to be the best choice.

If you’re racking up a high mileage, the fuel economy of diesel cars generally beats petrol or even hybrid models.

But if you’re making short journeys at low speeds through town, diesels can be a bit of a problem.

The diesel particulate filter (DPF) tends to become blocked more frequently with short journeys.

DPFs are designed to reduce emissions from diesel cars by capturing and then storing exhaust soot, but blockages can potentially leave you with expensive repair bills. So an electrichybrid or perhaps even a more economical petrol model might be better for you.

If you tend to make longer journeys, diesel isn’t just more economical than petrol, there are also plenty of discounts on diesel cars right now.

Demand for diesel models has fallen considerably, what with all the negative headlines as well as the higher taxes and charges.

You may be able to get a big enough discount to more than offset the higher costs of driving a diesel car. However, there’s always the risk that the taxes and charges that diesel motorists face may go up in the future.

If you’re buying a new diesel model, you’ll face higher road tax and parking surcharges. And if you buy an older model, you might be hit with higher company car tax and daily charges to drive into London and some other cities.

If your heart is set on diesel, perhaps because you are doing mainly long-distance driving along motorways, it might be best to choose a newer model that conforms with the latest Euro 6 emissions standards.

Owners of pre-2015 diesel cars face extra charges if they enter the clean air zones of certain UK cities. But you can avoid them if you opt for a diesel model that meets Euro 6 standards.

However, new, tighter Euro 7 emissions standards will be introduced in mid-2025. These standards mean drivers of these newer models could eventually be hit by the charges as well.

Diesel emissions: do diesel cars have catalytic converters?

For newer diesel models that comply with Euro 6 emissions standards, the problem of nitrogen oxide emissions has largely been solved.

The combination of an advanced catalytic converter, absorber and particle filter means the latest diesel cars should only emit a tiny output of harmful gases compared to the older diesels.

Diesel cars also produce less CO2 than petrol cars, making them comparatively less of a contributor to global warming. At one time, the government was even pushing diesel as an environmentally friendly alternative to petrol.

But the longer-term argument for diesel has been lost. The government wants to lower pollution and mitigate climate change. So from 2030, carmakers won’t be able to sell new diesel and petrol cars.

Costs have already increased for diesel drivers and they may rise further as more restrictions and even tighter emissions standards appear. Considering the recent sharp decline in demand for diesel cars, their used values may also fall more quickly than petrol models.

If you own a diesel car you might be thinking about buying something more sustainable. Or if you’re in the market for a new car, you could be considering what fuel to go for.

2030 ban on new petrol and diesel cars

Last year, the UK government made a commitment to ban the sale of new petrol and diesel cars by 2030.

This brought forward an earlier pledge by an ambitious five years. But hybrid models can still be sold until 2035. After that, every car sold in the UK should be fully electric, or as the government puts it “Fully zero emission at the tailpipe.”

The government says the plan will put the UK on course to become the fastest G7 country to decarbonise cars and vans, as it aims to mitigate climate change and improve air quality.

At the same time, the government announced £1.8bn in extra funding to encourage more of us to choose zero emission vehicles. That includes £1.3bn to accelerate the roll-out of electric charging points.

Diesel car bans in cities

In the UK, city councils have so far focused on deterring the use of older diesel cars through higher charges rather than outright bans.

German cities took a tougher line. From 2018, they began to ban diesel cars that fell short of Euro 6 standards and were therefore emitting higher levels of nitrogen oxides.

However, the extra charges faced by diesel drivers in UK cities can nevertheless be significant. Especially if you regularly have to drive into urban areas.

The Low Emission Zone (LEZ) was introduced for central London in 2008. The rules have been getting steadily stricter ever since.

In April 2019, the LEZ was replaced with what is now known as the Ultra Low Emission Zone (ULEZ), signalling an even tougher approach.

Drivers with diesel cars that do not meet Euro 6 standards – that’s to say most vehicles that were made before 2015 – need to pay a £12.50 daily charge to enter the ULEZ.

That’s on top of the £15 daily charge for driving into London’s congestion charge zone between 07:00-22:00. The ULEZ is expanding from October 2021 to cover a much larger area of London. This will stretch to, but won’t include, the North Circular Road (A406) and South Circular Road (A205).

Bristol is set to implement its Clean Air Zone from October 2021. After that date, drivers with diesel cars that don’t comply with Euro 6 standards will need to pay a £9 daily charge if they enter certain areas of Bristol.

Birmingham’s Clean Air Zone, introduced in June 2021, leaves drivers of diesel cars that don’t meet Euro 6 emissions standards with an £8 daily bill to enter central Birmingham.

The future of diesel cars

Diesel cars along with their petrol counterparts are in their end game. Governments around the world are drawing up plans to phase out internal combustion engines (ICE), and instead encourage the use of electric vehicles.

So, when will diesel cars be banned? The UK has gone further than most, with its pledge to ban the sale of new diesel and petrol cars by 2030 and hybrids by 2035. However, there’s no suggestion yet that the UK government or local authorities will ban the actual use of diesel cars.

Drivers with newer diesel cars that meet Euro 6 emissions standards should also continue to be exempt from the additional charges that some cities are levying. And for some time to come.

But it’s difficult to predict how legislation may change nationally and locally over the coming years. Especially as even stricter Euro 7 emissions standards are expected to come into being in 2025.

So, taxes and charges for diesel as well as petrol drivers may well increase again as authorities look to encourage motorists to adopt greener alternatives instead.

Should I sell my diesel car?

If you live in London, Bristol or Birmingham and have an older diesel car that doesn’t meet Euro 6 standards, it might be best to sell your car now and move on. On the other hand, if you live in a rural area and have a newer diesel car, then there’s less reason to sell just yet.

There is the risk, however, that the values of used diesel cars will fall at a faster rate than petrol cars over the coming years. More and more drivers may well ditch their diesels and the demand for the cars could fall further.

Not only that, new Euro 7 emissions standards from 2025 could push up costs for more diesel owners. Especially if the new standards become the new minimum requirement to enter UK cities’ clean air zones without having to pay a daily charge.

Even if you decide to hold on to your diesel car for the time being, it might be worth reconsidering the sale option again before 2025.

But remember, if you do decide to sell your diesel car, you'll need to let your car insurance provider know.

Pros & Cons of owning a diesel car 

Diesel engines are more fuel efficient than a comparable petrol engine, using up to 20% less fuel. So on this measure you get more for your money. This is despite diesel fuel being more expensive than petrol at the pump.

Newer diesel cars face higher road tax than petrol cars, though diesels made before April 2017 are taxed at a lower rate.

Petrol engines emit less pollutants like nitrogen oxides than their diesel counterparts, though diesel generates less CO2 emissions than petrol. Both diesel and petrol are much less environmentally friendly than green alternatives like battery electric vehicles, which produce no direct emissions at all.

Diesel tends to be noisier than petrol, though again, fully electric vehicles can make virtually no sound at all.

Diesel cars are less suited to drivers who will be making short journeys across town, as this type of use can block the diesel particulate filter.

Alternative options to diesel cars – electric cars and green cars

There are various alternatives to diesel cars. But it looks as though the UK government is set on encouraging us all to drive battery electric vehicles (BEV), given its investment in charging points infrastructure.

More than 20 new fully electric models will have made their market debut by the end of 2021. So there’s no shortage of choice in the all-electric category, including small city runabouts, sedans, SUVs and coupes.

It’s important to think about whether you’ll be able to charge your BEV cost-effectively. Ideally you need a home that’s suitable for installing a charging point for your car.

The overall cost can be a barrier to BEV ownership, as BEV purchase prices are generally higher than petrol or diesel cars. This also means that BEVs are on average more expensive to insure.

However, the cost of BEVs is expected to decline over the coming years. The technology is ever-improving and automakers will probably reap economies of scale as sales increase.

As a halfway house, some people are choosing plug-in hybrid or hybrid models for the time being. Hybrids offer increased flexibility, allowing you to fill up at the pump when you want to, instead of having to rely on charging points.

Waiting a little longer should mean that public charging infrastructure will be more widespread when you are finally ready to commit to a fully electric car. You could also find that you will get more for your money once electric cars have become more established.