When thinking about buying or leasing a new car, one of the most important decisions a driver must make is whether they want a diesel or petrol car.

There are lots of factors that need to be considered before making a purchase, including the performance, running costs and emissions associated with buying a diesel car.

This guide looks at all the facts, pros and cons and future of buying a diesel car to help you decide the best fuel type for you.

Basic facts about diesel cars

A diesel car is a type of vehicle that has a specific kind of internal combustion engine that relies on diesel fuel as opposed to petrol.

Diesel engines are renowned for their high torque (pulling power) and towing capacity, making them particularly well-suited for hauling heavy loads.

One of the standout features of diesel cars is their impressive fuel efficiency, with most models achieving higher miles per gallon (MPG) compared to their petrol counterparts.

This makes diesel vehicles an attractive option for long-distance driving and drivers who cover extensive miles annually.

Should I buy a diesel car?

To decide whether it’s worth buying a diesel car, it’s important to familiarise yourself with recent charges that impact diesel drivers.

The sale of new diesel cars will be banned in 2035, as originally outlined (for 2040) in the UK Air Quality plan for NO2 published in July 2017. This strategy also aims for almost every car and van on the road to be a zero-emissions vehicle by 2050.

The report stipulates that the efforts to reduce NO2 need to be targeted on the sources that make the biggest contribution, with road vehicles contributing about 80% of pollution at the roadside – with the plan citing diesel cars as the primary source of the problem.

Older diesel cars may not meet current emissions standards and could face restrictions in urban areas.

As part of the long-term strategy to reduce air pollution, a £10 toxicity charge was introduced in London’s Congestion Charge zone, which means that any diesel cars that don’t meet the Euro 6 emissions standards must pay an additional fee. This area of London became the first Ultra Low Emission Zone (ULEZ) in April 2019, resulting in an additional charge of £12.50 for most vehicle types that don’t meet the ULEZ emissions standards.

Many other cities have now introduced clean zone areas, a trend that is only going to grow given the aim laid out in the UK Air Quality Plan.

Source: gov.uk

Although your fuel type decision may be impacted by efforts to reduce air pollution, it’s mostly down to personal choice and your individual motoring needs.

Lower residual values on diesel cars are a reality

Diesel car residual values in the UK are likely to continue falling compared to petrol cars due to several factors:

Ban on New Diesel Cars: The UK government has announced a ban on the sale of new petrol and diesel cars from 2035, further reducing demand for diesel vehicles.

Dieselgate Scandal: The 2015 emissions scandal involving Volkswagen and other manufacturers tarnished the reputation of diesel engines, leading to decreased public trust.  

Stricter Emissions Standards: Governments are implementing increasingly stringent emissions regulations, making it more difficult and expensive for manufacturers to produce clean diesel engines.

Low-Emission Zones (LEZs): Many cities have introduced LEZs, charging fees for older, more polluting vehicles, including many diesel models.  

Economic Factors:

• Fuel Prices: While diesel fuel is often cheaper than petrol, the price difference has narrowed in recent years, reducing the cost advantage of diesel cars.
• Increased Cost of Ownership: Diesel cars can be more expensive to maintain and repair, especially as they age.  

Market Trends:

• Shift Towards Electric Vehicles: The growing popularity of electric vehicles is diverting consumer interest away from diesel cars.  
• Declining Demand for Diesel Cars: As a result of the above factors, demand for diesel cars has been steadily declining, leading to lower resale values.

While diesel cars may still offer some advantages in specific use cases, such as long-distance driving, the overall trend is towards lower residual values compared to petrol cars.

Ultimately, after 2035, only zero-emission vehicles, such as electric cars, will be available for purchase. This ban is part of the UK's commitment to reduce carbon emissions and combat climate change.

Consequently, the demand for diesel cars will decline significantly as consumers will be forced to buy new electric and other alternative fuel vehicles.

For this reason, lower residual values for diesel cars in the used car market in the future are inevitable.

Is it worth buying a diesel car?

Motorists can expect to spend an average of £100,000 on fuel during their driving life, regardless of whether they opt for diesel or petrol cars.

Nowadays, there’s little financial difference between the running costs of petrol and diesel cars than ever before. That said, it’s still true that diesel cars cost less in the long term for drivers with a high annual mileage and frequent motorway commute.

For urban drivers who do not cover long distances, a petrol car might be more suitable due to lower maintenance costs and better performance in stop-and-go traffic.

Servicing, insurance and depreciation all vary between petrol and diesel variants of the same car, with diesel models tending to cost anything between £1,000 and £2,500 more to purchase upfront than petrol counterparts.

The higher purchase price of diesel cars tends to be due to the extra technology needed to get them through emissions tests. Also, drivers are prepared to pay more in the interest of saving money in the long run.

While the pump price of petrol is generally lower, it’s outweighed for most by the increased efficiency of diesel engines that offer greater MPG.

Diesel car tax

The amount of car tax you pay for a diesel car in the UK depends on its CO2 emissions and whether it meets the Real Driving Emissions 2 (RDE2) standard for nitrogen oxide emissions.

First Year (First Licence):

• RDE2 Compliant: The tax rate will be based on the CO2 emissions band, similar to petrol cars.
• Not RDE2 Compliant: You'll pay a higher rate of tax, regardless of CO2 emissions.

Subsequent Years (Second Licence Onwards):

• Standard Rate: You'll pay the standard rate of £190 per year, regardless of the car's CO2 emissions or RDE2 compliance.

Important Note:

• Changes from April 2025: From April 2025, the first-year tax rates for higher-emission petrol and diesel cars will double. This means that some diesel cars could have significantly higher first-year tax costs.  

To find the exact tax rate for your specific diesel car, you can use the government's vehicle tax checker: https://www.gov.uk/check-vehicle-tax

It's crucial to check the specific rates and any potential changes before purchasing a diesel car.

For company cars, tax rates now go up to a maximum of 37% if the vehicle doesn’t meet specific fuel economy and emissions standards, as measured by the Worldwide Harmonised Light Vehicles Test Procedure (WLTP). This means diesel cars that fall short of these criteria will face the highest tax band, adding to the overall cost for company vehicle users.

The pros and cons of buying a diesel car with better fuel economy

Although the future of diesel may seem uncertain due to efforts to reduce air pollution, there are still some benefits to buying a diesel car.

These advantages include:

• Fuel efficiency. Diesel cars are more efficient than petrol vehicles in the long run, generally using 15-20% less fuel and resulting in lower running costs.
• CO2 emissions. While diesel fuel contains slightly more carbon per litre than petrol, the overall CO2 emissions of a diesel car tend to be lower than those of petrol.
• Diesel cars are best paired with an automatic transmission due to them offering more low-speed torque than petrol, making them ideal for motorway driving and long commutes. Diesel powered cars are particularly advantageous for long-distance driving due to their high torque and fuel economy.

The primary criticism of diesel cars is emissions, as diesels are known to produce harmful pollutants like nitrous oxides (NOx), particulate matter (PM) and carbon monoxide (CO). Although these pollutants are emitted by all cars with a combustion engine, including petrol and hybrid, diesels produce an average of 11.5 times the NOx of petrol variants.

Another ongoing issue is the diesel particulate filter (DPF) which can get clogged by exhaust soot over time. This soot has been linked to exacerbating asthma and other breathing conditions, leading to new MOT rules stating that any cars with a DPF emitting visible smoke or showing signs of tampering will not pass.

Some other downsides to diesel are:

• Increased cost. Diesel is more expensive to buy at the pump than petrol, and the higher purchase price of a diesel car can bump up insurance costs. New diesel cars also cost more to tax.
• Driving experience. Diesel engines tend to be noisier than petrol due to their high running pressure. However, recent developments have been made to reduce this on newer models.

So, should you buy a diesel car? Diesel cars are best suited to drivers that cover over 15,000 miles a year, but if you’re a low-mileage driver it may make more sense to consider alternatives.

If you’re looking for a vehicle that can offer a long-term investment, reduced upfront costs and lower carbon footprint, you may want to consider looking at hybrid or electric cars.

Advantages of diesel cars

Diesel cars come with a host of advantages that make them a popular choice among many drivers. Here are some key benefits:

• Better fuel economy: Diesel engines are generally more fuel-efficient than petrol engines, especially for long-distance driving. This means fewer stops at the pump and lower overall fuel costs.
• Higher torque: Diesel engines produce more torque than petrol engines, which is beneficial for towing and hauling heavy loads. This makes diesel cars ideal for tasks that require substantial pulling power.
• Longer engine life: Diesel engines are known for their durability and can last longer than petrol engines with proper maintenance. This longevity can translate into better long-term value.
• Lower CO2 emissions: Despite containing slightly more carbon per litre, diesel engines tend to produce fewer overall CO2 emissions compared to petrol engines, contributing to a lower carbon footprint.

Disadvantages of diesel cars

While diesel cars offer several benefits, they also come with some drawbacks that potential buyers should consider:

• Higher purchase price: Diesel cars are often more expensive to purchase than petrol cars, particularly newer models. This higher upfront cost can be a barrier for some buyers.
• Higher maintenance costs: Diesel engines are more complex and require more maintenance than petrol engines, which can lead to increased costs over time. Regular servicing is essential to keep a diesel engine running smoothly.
• Noise and vibration: Diesel engines can be noisier and produce more vibration than petrol engines, especially at idle and low speeds. This can affect the overall driving experience.
• Emissions concerns: Diesel engines have been linked to higher emissions of nitrogen oxides (NOx) and particulate matter, which can contribute to air pollution and have health implications.

Diesel fuel and emissions

Diesel fuel is a type of refined product derived from crude oil, known for its high energy density and fuel efficiency. However, it also has some notable drawbacks:

• Higher NOx emissions: Diesel fuel produces higher emissions of nitrogen oxides (NOx) and particulate matter than petrol fuel. These pollutants can contribute significantly to air pollution and have adverse health effects.
• Higher cost: Diesel fuel is often more expensive than petrol fuel, particularly in urban areas. This can add to the overall running costs of a diesel vehicle.

Alternative Fuels for diesel and petrol cars

With more technological advancements being made than ever before, there's hybrid, electric and LPG powered vehicles that offer a realistic alternative to petrol and diesel.

Electric cars offer the practicality and functionality of traditional petrol and diesel-engine cars, while emitting zero exhaust pollutants and lowering day-to-day running costs.

A hybrid car combines a conventional combustion petrol engine with an electric motor, working to reduce emissions, consume less fuel and lower road tax in comparison to traditional fuels.

As the demand for alternative fuels increases, more manufacturers are offering all-electric models alongside their petrol and diesel lineup.

Some of the top electric vehicles on the market include the BMW i3 for drivers looking for a premium high-performance hatchback, the Audi e-tron SUV and the Mercedes-Benz EQC.

Pure electric cars have no tailpipe emissions and plug-in hybrids have significantly lower emissions than petrol or diesel cars, so they're increasingly offering a better investment for environmentally conscious drivers.

In Summary...

Deciding whether it's worth buying a diesel car is a growing dilemma for drivers, but it's down to personal preference what fuel type you choose.

At AMT Auto, we're committed to providing a quality service that's tailored to you. If you're looking for a new car lease, contact our dedicated team today on 0113 3874241 to find your ideal match. Looking for a quality used car call us on 0113 3874250. Whatever your need we have a vehicle solution for you!