Should I Buy a Diesel Car in 2021?

Should I buy a diesel car in white text imposed over the image of a diesel fuel tank

The number of people buying diesel cars is down. As so many people turn away from the fuel, you might not think buying a diesel car is worthwhile. But should you still buy a diesel car?

According to SMMT, sales of diesel powered cars fell 55% in 2020. For comparison, 2019’s figures were already 22% down on 2018. Plus, the market share for diesel cars is only 16.2% – it was 25.2% in 2019.

So what went wrong? For years, the UK Government encouraged us to buy diesel cars through several schemes, and many of us did just that. Partly because diesel drivers can save an average of £132 a year on fuel costs (compared to petrol cars)!What’s more, CO2 emissions in new cars are down 31.2% since 2000. Modern diesel cars are as clean as their petrol equivalents – so why have we fallen out of love with the fuel?

After all, is it fair to brand the fuel as a toxic planet killer? Is it really as bad to buy a diesel car as we’re told?


Diesel Cars’ Fall From Grace

Many people see diesel powered cars as highly polluting. While they may produce 15-20% less CO2 (Carbon Dioxide) than petrol cars, they produce up to 8x more NOx (Nitrogen Oxides)! This is linked to poor air quality and over 40,000 unnecessary deaths a year.

These latest revelations have left many drivers feeling lied to about the benefits of diesel cars. There was a boom in sales between the 1990s and early 2000s – but now 3 in 5 diesel drivers have said they are thinking about switching fuel types, according to an RAC study. It doesn’t help that the stance on diesel has switch from positive to negative.

But the main reason for the widespread distrust of diesel cars is the fact that manufacturers can manipulate their emissions data.

The biggest scandal was VW’s ‘Dieselgate’. The German company manipulated emissions outputs to comply with Euro 6 regulations in lab tests – when their cars actually produced far more toxic gases under normal driving conditions!


exhaust blowing lots of smoke into atmosphere - main reason why people question if they should buy a diesel car or not
Many people cite the extra exhaust emissions a diesel car produces as a reason for not buying. But is this a fair criticism anymore?



Volkswagen installed a ‘defeat device’ to supress the recorded levels of NOx. It could recognise when it was running in a lab compared to running on the road. As a result, 400,000 UK drivers were horrified to discover that their VW Group vehicles were producing 9x more NOx gases than the official figures.

As a result of this, 91,000 drivers took VW to court, suing them for misleading and endangering the public with unsafe NOx levels. To this day, VW has paid out around €30 million in compensation.

This scandal shocked the world. It opened our eyes to the damaging impact diesel cars have on the environment and brought forward the development of electric cars, leading to the sales boom in the last few years.


Volkswagen logo
‘Dieselgate’ was a real low point for the VW group – especially as they were promoting the benefits of clean diesel at the time!


Now, it might look bleak for diesel cars, especially if you were wondering whether you should buy one. However, there are some positives for buying a diesel car – and not all the anti-diesel messaging is completely correct.


The Truth About Diesel Cars

Diesels may be naturally polluting, but there has been a big effort to limit the amount of toxic gases they produce. All modern diesels must comply with Euro 6 emissions regulations, and are fitted with Diesel Particulate Filters and AdBlue technology as standard.


Adblue tank in diesel car
Technological advancements, such as an AdBlue tank, make modern diesels just as clean as petrol equivalents


Euro 6 is the strictest emissions standard yet. It aims to reduce the levels of harmful exhaust emissions released into the atmosphere, and targets both petrol and diesel cars. However, Euro 6 meant diesels had to produce significantly less NOx to be considered roadworthy. It dropped from 180mg/km under Euro 5 to just 80mg/km.

As a result, every diesel car registered since September 2015 is designed to be as clean as possible. The petrol limit, for comparison, is 60mg/km – so the idea that diesels are significantly worse for the environment is wrong.

The one advantage diesels have over petrol cars is their incredible fuel economy. Diesel burns in a different way to petrol, meaning less fuel is used during the combustion process. This means that a diesel Vauxhall Corsa can achieve a staggering 88 miles per gallon! For comparison, the most fuel efficient petrol version can only manage 69 miles per gallon, with most struggling to reach 45 miles per gallon.


So, diesels aren’t as dirty as petrol cars, and they provide great value for money at the fuel pump. Does this mean you should always choose a diesel car? Well, the answer isn’t that simple. Your decision must take your driving habits into account.


Exploring Driving Habits

Before deciding whether you should choose a diesel car, answer the following questions:

  1. Do you drive in urban areas on a regular basis?
  2. Do you drive less than 12,000 miles a year?
  3. Do you do more short journeys over long distance driving?
  4. Do you do lots of stop/start journeys?

If the answer to most of these questions is yes, then you’re better off buying a petrol or electric vehicle. A diesel isn’t designed to work well under these conditions because of how the Diesel Particulate Filter (DPF) works.

The DPF traps excess exhaust emissions as soot, reducing the NOx output and your carbon footprint as a result. Eventually, this soot will build to a level that affects your car’s performance and the DPF will have to complete a process known as regeneration.

This process requires an extended period of high speed driving. This increases exhaust temperatures and burns the soot away – but it can’t happen at low speeds or during stop/start journeys.


Want to know more about how your DPF works and how you can avoid expensive problems? Check our our ‘Ultimate Guide to your Diesel Particulate Filter‘!


If you answered yes to most of these questions but own a diesel car already, you might be concerned about how your driving habits are affecting your DPF. Fortunately, there is a simple solution if you can’t engage the regeneration process on your own.

You can book a DPF clean through BookMyGarage!

From just £99, an expert mechanic will completely flush the insides of your car, removing the soot build up. A professional DPF clean is not only cheaper than a replacement DPF, which can cost upwards of £1,000, but it also improves your chances of passing your MOT. If your DPF is found to be too clogged and your car fails the emissions test included in an MOT, your car will fail. To avoid this stress and hassle at a time you need it least, book your DPF cleaning appointment through BookMyGarage today!


Book your DPF cleaning today with our quick and simple online booking tool!


When does buying a diesel car make sense?

It might seem like there are plenty of reasons against buying a diesel car, but very few in favour. Well, if you complete more than 12,000 miles a year, mainly through long journeys, choosing a diesel car may be a good idea.

The main advantage of a diesel is how well they conserve fuel during motorway driving. They’re much more fuel efficient at higher speeds and, although diesel is more expensive to buy at the pump, a single tank lasts longer. This saves you money in the long run!

There are other situations where you might benefit from driving a diesel car. These include:

  • Frequently towing a caravan or trailer.
  • Living in a more rural location where the emissions can’t cause as much damage to the health of others.
  • If you’re looking to buy a larger vehicle, such as an SUV or people carrier. The diesel versions of these cars are much more effective than the petrol equivalents, thanks to their frugal use of fuel. As these vehicles usually have large fuel tanks which are expensive to fill, anything you can do to avoid unnecessary fuel costs is worthwhile!


If a diesel car seems like the best option for you, you might be looking to start buying one in the near future. However, it’s worth considering the future of the fuel before making a purchase.


Person counting cash at a petrol station with the fuel pump filling the car
If you’re already thinking about how much money you can save on fuel costs, you might want to consider the future of diesel before making your final decision



The Future of Diesel Cars

The automotive landscape is changing dramatically within the next ten years, including the future of diesel cars. The UK Government brought forward the ban on combustion engine sales to 2030 last year. Although, there’s no word on whether second-hand diesel sales can continue or if people will have to replace all combustion vehicles in 2030.

Besides, the SMMT says there are 13.8 million vehicles on the UK roads. They’re not all going to disappear overnight!

This massive change might put you off entering the market, so late in the life cycle. There are also other changes which specifically affect diesel vehicles, including:

  • The Euro 7 emissions standard which is being introduced in 2025. This will be even stricter than the current Euro 6 standard, but will give drivers the confidence to buy an even cleaner diesel car.
  • Increase in first year car tax for diesel vehicles. Plus, the 2018 tax changes means all older, more polluting cars will pay far more car tax.
  • More urban areas are introducing Clean Air Zones (CAZ), restricting access to some areas for more polluting cars.


Clean Air Zones

Two CAZ’s are confirmed for 2021.

  • Bath – 15th March 2021. All vehicles except cars and bikes have to pay if they don’t meet the required emissions standards. Taxis, minibuses and vans will be charged £9 a day and all other vehicles charged £100 a day to enter.
  • Birmingham – 1st June 2021. All vehicles except motorbikes have to pay. Cars will pay £8 a day, with HGVs paying £50.

You can find more information about CAZs, including what areas they affect, on your local council website.


Other cities are also considering CAZs.

  • Bristol. This project is still in the consultation stage, but looks highly likely.
  • Manchester. This project is confirmed and the proposed opening date is 2022.


In Scotland, the plan is to open several Low-Emissions Zones between February and May 2022. These carry a penalty notice to discourage cars which don’t meet the standards from entering. You should check what emissions standards your car meets before travelling into one. The following cities have been chosen:

  • Aberdeen
  • Dundee
  • Edinburgh
  • Glasgow


Ultra-Low Emissions Zone (ULEZ)

This affects drivers in Central London and covers the same area as the Congestion Charge. However, it is a 24/7 zone, and entering at 11pm one day and leaving at 1am the next incurs two charges. It is £12.50 per car, and £100 a day for larger vehicles such as lorries, on top of the Congestion Charge!

This will extend to the North and South circular roads from October 2021. Also, a London-wide Low-Emissions Zone came into force on the 26th October 2020. This affects all lorries and vehicles over 3.5 tonnes.

You’ll be charged for entering the ULEZ if your car doesn’t meet the following emissions standards:

  • Euro 4 for petrol vehicles
  • Euro 6 for diesel vehicles
  • Euro 3 for motorbikes


If you live in, or regularly travel into, any of these areas, buying a second-hand diesel car might not be the best idea. If you still think you should buy a diesel car, here’s what to look out for when making a purchase.


long traffic jam in a town centre
If you regularly encounter scenes like this in an urban area, a diesel car might not be the best idea for you!


Buying and Selling a Diesel Car

A new diesel car is more expensive to buy than a petrol car. All that extra technology to improve its emissions output isn’t cheap to build, so they aren’t cheap to buy! What’s more, a diesel’s value depreciates faster than a new petrol car – although not as much as many first feared.

If you’re looking at second-hand diesel cars, be aware that some older vehicles can damage the environment. If it only meets Euro 4 standards (registered pre-2005), it may produce a significant amount of NOx. Climate conscious buyers should never buy one of these models. Many used car websites, such as Whatcar?, allow you to filter by emissions output so you find a clean diesel car.

If you’re looking to sell a diesel, buyers will still pay a reasonable price. However, you might not feel comfortable doing so if it’s an older model. If you’re in this situation, many manufacturers now offer ‘scrappage schemes‘ for old diesels. These can knock a few thousand pounds off the cost of a new diesel car when you trade in your old one.


How to get the best deal

The best way to buy any car is to do your research and focus on what you want out of your purchase. That way, you’ll always get the best deal. Understanding your driving habits can help you work out exactly what sort of car is best for you. Always consider what you need before even thinking about buying.


For more tips on how to get the best deal on a new or used diesel car, check out our ‘Ultimate Guide to Buying a Car‘! 



There is no simple answer to the question ‘should I buy a diesel car?’ A lot of it depends on your current and future driving habits and your level of climate consciousness. Buying a modern diesel car brings great benefits to your fuel economy, and the DPF reduces your carbon footprint significantly.

However, you have to take proper care of it. This includes booking a DPF clean every 6-9 months. This will keep your DPF functioning properly and save you money on expensive repairs. You’ll also avoid a stressful MOT failure! You can compare DPF cleaning prices from thousands of garages across the UK simply by entering your car reg and post code.

Mandy Weston

Mandy is an ex-mechanic, with 22 years’ experience in the motor industry. As an in-house motoring expert, Mandy is the go-to woman for any relevant questions that our customers have; both garages and drivers. From specific problems with your car to general maintenance, Mandy is a reliable source of information and advice. Her passion for motoring is a huge factor to her success and the huge wealth of knowledge that she has. She now uses her remarkable grasp of the industry to write regular content for our readers to help drivers understand their car better, avoid being ripped off by garages and save money on their motoring requirements.