During the noughties, buyers switched from petrol cars to diesel in large numbers, incentivised by lower car tax for diesel cars, thanks to their reduced CO2 emissions. However, the other pollutants from diesel car exhausts, and their impact on lower air quality standards, have led to legislation that means owners of diesel cars have to pay to drive in clean air zones around the country.
But the appeal of diesel cars to some drivers remains, because they are still a more practical and economical option for many.
In this article we will assess the viability of diesel cars in the run-up to the ban on their sale in 2030 (or 2035, but probably 2030) and what types of drivers are still best suited to them.
Reasons to get a diesel car
For some drivers, diesel cars still represent the best choice of vehicle.
Diesel cars still make sense for drivers who tend to cover longer distances. If you cover more than 12,000 miles a year, the additional costs around a diesel car will probably be outweighed by any savings you make from its more economical fuel consumption.
Diesel vehicles are also particularly suited to towing, because the engines produce the kind of power that is good for pulling heavy loads. They can usually tow larger loads than their equivalent petrol cars, too, coping better with a caravan, horsebox or heavy trailer.
Diesel cars tend to be hard wearing, because the engines are robust, better lubricated and suffer less from being used regularly. The way in which diesel engines work, and the fact that components tend to be more robust, also makes them more durable than petrol engines. Indeed, a petrol engine will probably need major repairs or maintenance around the 200,000-mile mark, while a diesel can last five times as long, hitting a million miles before any serious work needs doing.
Allied to the advantage over long distances, diesel cars make good company cars. With the current company car tax regime still linked to CO2, diesel vehicles may still allow company car drivers to save money. But EVs are the way to go for smart company car drivers thanks to the huge BiK benefits.
When it comes to buying a used car, larger diesel vehicles tend to hold their value better than their petrol counterparts, the latter often being more expensive to run. Newer diesel cars with a Euro 6 engine standard are also holding their value, because owners don’t have to pay to drive into a Clean Air Zone or the London ULEZ.
Of course, there’s a big question around how used diesel car prices will react after the 2035 ban on the sales of new diesels. In 2021, there were 11.6m diesel cars in the UK, with numbers declining year-on-year: the laws of supply and demand suggest that as diesels become less commonplace, the cost of those remaining could hold up well.
Diesel cars return better fuel consumption figures than their petrol equivalents, so the larger the car, the more savings owners will make. For example, a diesel-engined SUV will often return twice the fuel economy of a petrol equivalent. This means that if a diesel suits your lifestyle, it is also a cheaper alternative to a petrol car.
Reasons not to get a diesel car
It’s fair to say that for most drivers, diesel cars are not the right alternative, for plenty of very good reasons:
Living in London or another CAZ
If you live in or around London, you’ll be aware that the capital’s Ultra-Low Emissions Zone (ULEZ) was recently extended to cover every borough – which is most roads within the M25. There are also 14 other Clean Air Zones (CAZ) in towns and cities in the UK, a number that will expand in the coming years.
Different zones have different rules, according to local needs, but what they mean for drivers is that if you have an older diesel car (with Euro 4 or Euro 5 engine standards), you will have to pay to drive into the zone. If you live in that zone, it means paying every time you drive. In London, that means £12.50 just to drive down the street.
You can drive in CAZ and ULEZ in diesel cars with a Euro 6-standard engine, or most petrol-engined cars (anything from Euro 4 onwards), but clearly the best alternative is a zero-emissions vehicle. After all, in a zone designed to improve air quality, an EV with no tailpipe emissions is the ideal car.
Newer diesel cars are cleaner (but more expensive)
The reason why older diesel cars are being charged for travelling in areas that have poor air quality is that they emit nitrogen oxides (NOx) and fine particulate matter (PM). Newer Euro 6 diesels have new engine technology that filters more of these out of exhaust fumes, which is why they’re exempt from paying to drive in a CAZ. That said, a newer diesel, even used, isn’t cheap, so you’re just paying more upfront (or monthly) compared to shelling out £12.50 every day you drive.
If you usually only drive short journeys
If you make a lot of short journeys and don’t drive at least 12,000 miles a year, a diesel is not a good option for you. Diesel engines only fully warm up after a few miles, so a lot of short journeys can damage the engine (leading to expensive repairs). And unless you cover the miles, the additional up-frontmcost of a diesel car over an equivalent petrol one, plus the higher cost of diesel fuel, just won’t add up.
If you do mostly drive short distances, an EV is a far better option: not only is it cleaner, but you won’t suffer from the ‘range anxiety’ that some EV drivers experience.
The problem with older diesels is that their exhausts emit a lot of pretty nasty pollutants, including NOx and PM. These have contributed to air pollution being the leading environment health hazard in the UK, causing up to 40,000 early deaths a year.
The principle of ‘polluter pays’ that we have used for decades means that the drivers of diesel cars have to pay to use their cars in a CAZ.
But there’s also an environmental angle. If you own an old, polluting diesel, do you really want to be driving around in it? More and more of us are feeling that kind of environmental guilt these days, but we can’t all afford EVs – and there aren’t enough of them on the market yet, even if we could.
If, on the other hand, you can afford to switch from an older diesel to an EV, the sooner you do so the better, for the environment and your pocket.
They’re more expensive to run than EVs
Understandably, many drivers complain of the high cost of switching to an EV, because the sticker price, or monthly payment, is higher than that of an equivalent diesel car. Used EVs are also still relatively rare.
However, while switching to an EV seems expensive, it might not be as expensive as you think, when you take the total cost of ownership (TCO) into account. EVs have fewer moving parts, so repairs and maintenance are less expensive; charging an EV from your domestic tariff – even at recent high prices – is about half the cost of filling a tank with diesel; and demand for used EVs means that they command a relatively high resale value.
Add those together and most owners will find that running an EV is, in fact, not as pricey as a diesel.
Pay less tax
If you drive an older diesel, you pay more for your car tax (officially known as vehicle excise duty, or VED) every year, because you’re taxed on the amount of CO2 your car emits. As the Euro engine standards have improved, many newer diesels are cheaper to tax. EVs are cheaper still, because owners don’t pay VED.
And, of course, there’s all the money from the cost of a litre of diesel that goes to the government. Yes, there’s VAT on domestic electricity, but it’s nothing like the amount you pay on fuel at the pump.
Is there a future for diesel cars?
With just over 11m diesel cars on British roads, they’re going to be with us for some time yet – especially as the engines are more hard-wearing than in petrol cars and can keep on running as long as the cars around them stay intact.
The number of diesel cars in the UK has now been in decline for three years, which is likely to continue right up to the current 2035 ban on new diesels being sold. There are plenty of years of diesel sales to come, but with fewer models being on sale and the public taste for them falling away, the fall in total numbers could well accelerate.
Beyond 2035, how long diesel cars survive is a question that many are struggling with. How long will car manufacturers continue to make replacement parts? How long will oil companies continue to refine and sell diesel fuel? How quickly will we all adopt EVs?
Owning a diesel car is likely to be a viable option for people well into the 2040s, we suspect. The oil companies, at the very least, will be drilling and pumping to fill diesel cars as long as they’re on the road.
But don’t be surprised to see ‘diesel shaming’ become a thing in the 2030s, as many people become less tolerant of those fellow citizens who don’t commit to the concept of net zero.
So, is it worth buying a diesel car?
Every car owner is different, with different needs and usage patterns, so there’s no single definitive answer that works for everyone. However, as a rule of thumb:
You should buy a diesel car if:
- You’re a high-mileage driving clocking up over 12,000 miles a year
- Your car journeys tend to cover long distances
- You regularly use your car to tow
- You want a car with a durable, hard-wearing engine
- You want a fuel-efficient car
- You drive a company car and can’t have an EV
You shouldn’t buy a diesel car if:
- You live near the London ULEZ or another CAZ
- You mainly drive short distances
- You don’t drive many miles over the course of a year
- You want the lowest possible running costs
- You want to pay less tax
- You’re concerned about air quality and the environment
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