Diesel Cars in the UK: Still a Smart Choice?

In the noughties, diesel cars enjoyed a significant surge in popularity across the UK, with buyers flocking away from petrol models. This shift was largely driven by incentives like lower car tax, a direct result of their reduced CO2 emissions compared to petrol counterparts. However, the narrative has dramatically changed. The focus has broadened to include other harmful pollutants from diesel exhausts, such as nitrogen oxides (NOx) and fine particulate matter (PM), which have a detrimental impact on air quality. This growing concern has led to stricter legislation, meaning owners of older diesel cars now face charges to drive in Clean Air Zones (CAZs) and the London Ultra-Low Emission Zone (ULEZ) across the country.

Despite these challenges and the looming ban on the sale of new petrol and diesel cars, a certain appeal of diesel vehicles persists for some drivers. They are still seen as a practical and economical option for specific usage patterns. This article will thoroughly assess the viability of diesel cars in the run-up to the 2035 ban on their sale and explore which types of drivers might still find them to be the most suitable choice in today's evolving automotive landscape.

The End of an Era? Diesel's Journey in the UK

The journey of diesel cars in the UK has been one of significant highs and lows. From being championed as the cleaner, more efficient alternative due to their lower CO2 output, they have now become the focus of intense scrutiny regarding air quality. The initial push towards diesel was a direct response to climate change concerns, as their superior fuel economy translated to fewer greenhouse gas emissions per mile. This led to a boom in sales, with millions of diesel cars hitting British roads.

However, scientific understanding and public awareness of air pollution have evolved. While CO2 is a greenhouse gas, NOx and PM are directly harmful to human health, contributing to respiratory illnesses and other serious conditions. This shift in focus led to the introduction of measures like the ULEZ in London and various CAZs in other major UK cities, designed to deter older, more polluting vehicles from entering designated areas. These zones charge drivers of non-compliant vehicles, primarily older diesels (typically pre-Euro 6), a daily fee. This has undeniably impacted the perceived desirability and practical ownership of diesel cars, particularly for urban dwellers. The number of diesel cars on UK roads has been steadily declining year-on-year for the last three years, signalling a clear trend away from this fuel type.

Why Diesel Still Appeals: The Enduring Advantages

Despite the negative press and increasing restrictions, diesel cars continue to hold significant advantages for a specific segment of drivers. Their inherent characteristics make them uniquely suited for certain tasks and driving habits, offering benefits that petrol and even electric vehicles sometimes struggle to match.

Long-Distance Journeys

For drivers who regularly cover substantial mileage, particularly on motorways and A-roads, diesel cars remain an exceptionally sensible choice. Their superior fuel economy means fewer stops at the pump and lower overall fuel bills compared to equivalent petrol models. If your annual mileage consistently exceeds 12,000 miles, the initial additional cost of a diesel car, or the higher price of diesel fuel per litre, is often offset by the significant savings made on fuel consumption. Diesel engines operate more efficiently at consistent speeds, making them ideal companions for long commutes or extensive travel.

Towing Capabilities

One of the most compelling reasons to choose a diesel vehicle is its remarkable suitability for towing. Diesel engines are renowned for producing high levels of torque, particularly at lower RPMs. This characteristic makes them incredibly effective at pulling heavy loads, whether it's a caravan for family holidays, a horsebox, or a large work trailer. Diesel cars can typically tow larger and heavier loads than their petrol counterparts of similar size and power, and they handle the strain with greater ease, providing a more stable and less stressed towing experience.

Durability and Longevity

Diesel engines are often described as workhorses, and for good reason. They are inherently robust and built to withstand significant stress. The way in which diesel engines operate, with higher compression ratios and stronger internal components, contributes to their exceptional durability. Furthermore, the fuel itself provides a degree of lubrication to certain engine parts, reducing wear and tear. This robustness means diesel engines tend to suffer less from regular, heavy use. While a petrol engine might start requiring major repairs or significant maintenance around the 200,000-mile mark, a well-maintained diesel can potentially last five times as long, with some examples reaching a million miles before needing serious overhaul work. This longevity can translate to lower long-term depreciation for high-mileage drivers.

Company Cars

For some time, diesel cars were the go-to option for company car schemes, largely due to the company car tax regime being linked to CO2 emissions. While electric vehicles (EVs) now offer unparalleled Benefit-in-Kind (BiK) tax advantages, making them the smart choice for savvy company car drivers, diesel vehicles may still offer some savings for those whose company policies or specific needs don't yet align with an EV. The combination of long-distance efficiency and historical tax benefits kept them a viable option for a period, though this landscape is rapidly shifting.

Used Values

When it comes to the used car market, larger diesel vehicles have historically tended to hold their value better than comparable petrol models. This is often because the running costs of larger petrol cars can be significantly higher. Crucially, newer diesel cars that meet the Euro 6 engine standard are also demonstrating strong residual values. This is directly attributable to their exemption from charges in most Clean Air Zones and the London ULEZ, making them a more attractive proposition for buyers who need to drive in or around these areas without incurring daily fees.

Of course, a significant question mark hangs over how used diesel car prices will react after the 2035 ban on the sale of new diesels. In 2021, there were still 11.6 million diesel cars in the UK, a number that is now declining. The basic laws of supply and demand suggest that as diesels become less commonplace on the roads, the cost of the remaining compliant models could indeed hold up well, especially for those who still require their specific advantages.

Fuel Efficiency

Perhaps the most straightforward advantage of diesel cars is their superior fuel consumption figures compared to their petrol equivalents. This efficiency becomes even more pronounced in larger vehicles. For instance, a diesel-engined SUV will frequently return double the fuel economy of a similarly sized petrol SUV. This means that if a diesel car genuinely suits your lifestyle and driving habits, it presents a significantly cheaper alternative to a petrol car in terms of day-to-day fuel costs.

The Downside of Diesel: When to Avoid

While diesel cars offer certain benefits, it's equally important to understand their significant drawbacks, which, for the majority of drivers, now outweigh the advantages. The landscape for diesel ownership has become increasingly challenging, especially in urban environments.

Living in London or Another Clean Air Zone (CAZ)

If your daily life or regular travel takes you into or around London, you will be acutely aware of the Ultra-Low Emission Zone (ULEZ). This zone was recently expanded to cover every borough within the M25, meaning most roads in the capital are now subject to its charges. Beyond London, there are also 14 other Clean Air Zones (CAZs) implemented in towns and cities across the UK, a number that is expected to grow in the coming years. While the specific rules vary based on local needs, the common thread is that owners of older diesel cars (typically those with Euro 4 or Euro 5 engine standards) must pay a daily charge to drive within these zones. For residents within these zones, this means incurring a charge every single time you drive your car. In London, this can amount to £12.50 just to drive down your street, quickly adding up to a substantial monthly or annual cost.

It's worth noting that diesel cars with a Euro 6-standard engine are generally exempt from these CAZ and ULEZ charges, as are most petrol-engined cars (from Euro 4 onwards). However, the underlying principle of these zones is to improve air quality, making a zero-emissions vehicle (like an EV) the ideal choice. An EV produces no tailpipe emissions, aligning perfectly with the environmental goals of these urban areas.

Newer Diesel Cars are Cleaner (But More Expensive)

The reason older diesel cars are penalised in areas with poor air quality is their emissions of harmful nitrogen oxides (NOx) and fine particulate matter (PM). Newer Euro 6 diesel engines feature advanced technology, including selective catalytic reduction (SCR) and diesel particulate filters (DPF), which significantly filter out more of these pollutants from exhaust fumes. This is why they are exempt from current CAZ charges. However, acquiring a newer diesel, even a used one, often comes with a higher upfront cost compared to older models. While you might save on daily CAZ charges, you're essentially paying more upfront (or in higher monthly finance payments) compared to the alternative of paying £12.50 daily for an older, non-compliant vehicle. This higher purchase price can negate some of the perceived long-term savings.

If You Usually Only Drive Short Journeys

A diesel car is simply not a good option if your driving mainly consists of short journeys, and you don't cover at least 12,000 miles a year. Diesel engines are designed to operate most efficiently when fully warmed up, which typically takes a few miles. Frequent short trips, where the engine never reaches its optimal operating temperature, can lead to issues such as clogged Diesel Particulate Filters (DPFs). DPFs require regular regeneration cycles (burning off trapped soot) which only occur during longer, higher-speed drives. If these cycles are interrupted or don't happen often enough, the DPF can become blocked, leading to expensive repairs or replacement. Furthermore, for low mileage drivers, the additional upfront cost of a diesel car over an equivalent petrol one, coupled with the generally higher cost of diesel fuel, means the economic benefits simply won't materialise.

For those who primarily drive short distances, an EV is a far superior option. Not only are they cleaner with zero tailpipe emissions, but they are also highly efficient for stop-start city driving and short trips, and you won't experience the 'range anxiety' that some EV drivers might feel on longer journeys, as your charging needs are easily met at home.

Environmental and Health Concerns: Pollution

The core problem with older diesels lies in the noxious pollutants their exhausts emit, particularly NOx and PM. These have been identified as major contributors to air pollution, which is now considered the leading environmental health hazard in the UK, implicated in up to 40,000 early deaths per year. The long-standing principle of 'polluter pays' has been applied to diesel drivers, necessitating charges for using their cars in CAZs. Beyond the financial aspect, there's a significant environmental and ethical dimension. Owning an old, polluting diesel can lead to a sense of environmental pollution guilt, a feeling increasingly shared by many. While not everyone can afford the switch to an EV, and the market for used EVs is still developing, the environmental impact of older diesels is undeniable. If you are in a position to transition from an older, more polluting diesel to an EV, doing so sooner rather than later benefits both the environment and your wallet in the long run.

They’re More Expensive to Run Than EVs (Overall)

Many drivers voice concerns about the high upfront cost of switching to an EV, as the sticker price or monthly finance payment is often higher than that of an equivalent diesel car. The used EV market is also still relatively new, meaning fewer options and higher prices for second-hand models. However, when considering the Total Cost of Ownership (TCO), the picture changes significantly. EVs have fewer moving parts than internal combustion engine (ICE) cars, leading to lower maintenance and repair costs. Charging an EV from your domestic electricity tariff, even with recent price increases, is roughly half the cost of filling a tank with diesel. Furthermore, the growing demand for used EVs means they are commanding relatively high resale values. When these factors are combined, most owners will discover that running an EV is, in fact, less pricey over its lifetime than a diesel car, despite the initial outlay.

Higher Tax Burden

If you drive an older diesel car, you generally pay more for your annual car tax, officially known as Vehicle Excise Duty (VED). This is because VED is taxed based on your car's CO2 emissions. As engine standards have improved, many newer diesels (Euro 6 compliant) are cheaper to tax. However, EVs are the cheapest option of all, as owners pay no VED at all. Beyond VED, a significant portion of the cost of a litre of diesel at the pump goes directly to the government in fuel duty and VAT. While there is VAT on domestic electricity used for charging, it is nowhere near the amount you pay on fuel at the pump, further contributing to the lower running costs of an EV.

The Future of Diesel: Beyond the Ban

With just over 11 million diesel cars still on British roads, they are certainly not disappearing overnight. Given the inherent hard-wearing nature of diesel engines, many of these vehicles will continue to run for years to come, potentially outliving the cars around them. However, the number of diesel cars in the UK has been in decline for three consecutive years, a trend that is almost certain to continue right up to the current 2035 ban on the sale of new petrol and diesel cars (the original 2030 target was recently pushed back). While there are still years of diesel sales ahead, the decreasing number of models available and the public's waning appetite for them could accelerate this decline in total numbers.

The question of how long diesel cars will survive beyond 2035 is complex and subject to many variables. How long will car manufacturers continue to produce replacement parts for a dwindling fleet? How long will oil companies find it economical to refine and sell diesel fuel to a shrinking market? And how quickly will the mass adoption of EVs truly take hold across all segments of society? Our suspicion is that owning a diesel car is likely to remain a viable option for people well into the 2040s. Oil companies, at the very least, will continue to drill and pump to supply diesel fuel as long as there's a demand from vehicles on the road.

However, it wouldn't be surprising to see 'diesel shaming' become a more prevalent social phenomenon in the 2030s. As more people commit to the concept of net zero emissions, there may be increasing social intolerance towards those who continue to drive older, more polluting vehicles, even if financially constrained.

Making the Right Choice: Is Diesel For You?

The decision of whether to buy a diesel car is highly individual, depending on your unique driving needs, usage patterns, and priorities. There is no single definitive answer that applies to everyone. However, as a general rule of thumb, here's a breakdown to help you make an informed decision:

You should consider a diesel car if:

• You are a high-mileage driver, clocking up over 12,000 miles a year.
• Your car journeys predominantly involve long distances.
• You regularly use your car for towing heavy loads.
• You prioritise a car with a durable, hard-wearing engine and long lifespan.
• You seek a highly fuel-efficient car for extensive travel.
• You drive a company car and an EV is not currently a viable option for you.

You should probably avoid a diesel car if:

• You live within or frequently drive into the London ULEZ or another UK Clean Air Zone (unless it's a Euro 6 compliant model).
• Your driving mainly consists of short distances or urban trips.
• You don't cover many miles over the course of a year.
• You are seeking the absolute lowest possible running costs in the long term.
• You want to pay less in annual car tax (VED).
• You are highly concerned about local air quality and your environmental impact.

Diesel vs. Alternatives: A Quick Comparison

Frequently Asked Questions About Diesel Cars

Q: Are diesel cars banned in the UK?

A: No, diesel cars are not currently banned from UK roads. However, the sale of new petrol and diesel cars will be banned from 2035. Additionally, older diesel cars (typically those that don't meet Euro 6 emission standards) are subject to daily charges if driven within designated Clean Air Zones (CAZs) and the London Ultra-Low Emission Zone (ULEZ). Euro 6 compliant diesels are generally exempt from these charges for now.

Q: Will diesel fuel disappear from UK pumps soon?

A: It's highly unlikely that diesel fuel will disappear from pumps in the near future. While the number of diesel cars on the road is declining, there are still over 11 million of them, and many are durable enough to last well into the 2040s. As long as there's a significant demand, oil companies will continue to refine and supply diesel fuel, though the network of filling stations might gradually consolidate over time.

Q: Is a Euro 6 diesel car a good choice for urban driving?

A: While a Euro 6 diesel car is exempt from current CAZ and ULEZ charges, making it 'legal' for urban driving without penalty, it's still generally not the ideal choice for predominantly urban or short-distance driving. Diesel engines perform best on longer runs where they can warm up fully and regenerate their Diesel Particulate Filters (DPFs). Frequent short journeys can still lead to DPF issues and reduced fuel efficiency compared to their optimal performance. For urban driving, an electric vehicle or a compact petrol car would typically be a more suitable and environmentally conscious option.

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