There’s been a big push towards electric vehicles, with the evolution of government grants and support schemes to assist drivers making the transition to an EV. But we know that electric vehicles aren't the right choice for all drivers in every business so we’ve also taken a look at the benefits and costs of diesel specifically in this guide.
What is diesel?
Diesel is one of the two main traditional fuels used in vehicles that have a combustion engine.
It's been in and out of favour with the UK government over the years, with there initially being tax breaks for diesel vehicles due to lower CO2 emissions which were then reversed when the overall environmental impact was found to be worse. This doesn't mean you should never choose a diesel vehicle and in fact there are circumstances when you might find a diesel car will be better for particular drivers in your fleet. We've explored some of these benefits below.
What are the different types of diesel?
In the UK there are two types of diesel available. The main type available at the pumps is city or low sulphur diesel and the second is premium diesel.
City / low sulphur diesel is the standard fuel type whereas premium diesel has a higher cetane rating which means it will burn more quickly and efficiently as well as containing cleaning agents and lubricant that reduce soot particles and oily residue build up in the engine and fuel system. It can be useful to fill up with premium diesel every tenth tank or so, to help reduce build up in the car's system but in general, provided drivers are regularly running the vehicle at high speed over a significant distance, this should not be an issue.
Benefits of diesel vehicles
There are a number of benefits that diesel engines can provide your fleet.
Diesel has better fuel economy than petrol and obviously doesn't require charging like an EV, so if you need a vehicle for a driver who travels long distances regularly or has a high annual mileage, it's a compelling choice alongside a fuel card scheme.
Typically, diesel engines are slightly larger and more powerful making them able to achieve greater torque, so they have better overtaking power and towing abilities. This makes them a good choice if you need a vehicle that is likely to be towing regularly.
A diesel car will also have lower CO2 emissions than petrol equivalents, however this is countered by higher levels of other emissions. We’ll explore these in further detail below.
Considerations with a diesel vehicle
As we as the benefits listed above there are a few other aspects of a diesel vehicle that you’ll need to consider when deciding if it's the right choice in certain circumstances.
Diesel vehicles are typically a little more expensive than petrol engines, which means that the cost of them will be higher, no matter whether you're purchasing or leasing them.
Servicing and maintenance can also be a little higher when you opt for diesel as there are additional components like a diesel particulate filter (DPF) that other engine options don't have.
The diesel particular filter helps reduce emissions, but it also requires a particular type of driving in order to prevent it from becoming clogged. For example, if the vehicle is going to be used for constant, low-speed urban driving then the DPF will quickly become clogged and need replacing. On the flip side, if the vehicle is driven regularly on a higher speed road then it's less likely to become blocked.
Another consideration that you'll want to make is whether your business, or the driver’s home address, is located in a city that has, or is introducing, a low emission or clean air zone. We recommend checking your business address and the driver’s address against areas where diesel cars are more heavily penalised, by higher tariffs.
If the intended driver lives in an area with a residential parking permit scheme then they'll also want to check that their local authority isn’t applying a diesel surcharge, as some apply a higher rate for diesel vehicles.
Will diesel cars be banned?
Yes, they will. As part of the government's commitment to having all new vehicles being sold as zero emission ones the sale of new diesel vehicles will be stopped from 2030, (with a total ban on all non-zero-emission vehicles including hybrids following in 2035).
However, the sale of used diesel vehicles will still be allowed after this date until they gradually phase out, as fleets and private vehicles are updated to newer models.
Diesel vehicles and the environment
One of the biggest concerns for drivers and businesses looking at expanding their fleet when considering a diesel engine, is the environmental impact they have.
Although modern diesel engines are much cleaner than the original models, they're still considered to be the most polluting of engine options available.
Diesel cars produce and emit less CO2 than a petrol engine however they emit more of other pollutants like nitrogen oxide. These pollutants are why modern diesel vehicles are fitted with a diesel particulate filter (DPF) which cuts down on the emissions the vehicle produces. As mentioned above it’s important to bear in mind the conditions needed to prevent the filter from being clogged.
Additionally, most diesel vehicles are also fitted with technology that converts most of the nitrogen oxide into nitrogen and oxygen before reaching the exhaust and these are both harmless to the environment.
Car manufacturers are working hard to continue to reduce the environmental impact of their business as well as that of their vehicles and diesel cars are cleaner than ever before with many now complying with the Euro 6 emission standards.
If you want to find out more about the impact of CO2 and why it’s important that you consider this as well as the other emissions of a vehicle then take a look at this guide.
Diesel vehicles and tax
The amount of road tax (Vehicle Excise Duty) required for a vehicle is highly dependent on its emissions, making diesel models historically more expensive to tax annually. Following the 2026 VED updates, the standard annual flat rate for petrol and diesel cars sits at £200. However, the first-year "showroom tax" rates have risen sharply, meaning high-emission or non-compliant diesel vehicles can face a first-year tax spike of up to £5,690 depending on their g/km output. Brand-new EVs pay a low £10 first-year rate. From year two onwards, they move to the standard flat rate of £200 per year.
This makes the budget implications of choosing diesel highly significant if your business purchases vehicles outright. If you have leased vehicles in your fleet, you won't need to be as concerned about managing the road tax directly, as this is paid by the lease funder. However, keep in mind they may invoice you the difference if there is a mid-contract rise in road tax from the initial registration date.With a vehicle that's being driven by one of your employees as a company car, it would also be wise to consider the company car tax (Benefit-in-Kind) implications. Company car tax is in part based on the CO2 emissions of a vehicle, and so if other factors also align, you might end up opting for a petrol rather than a diesel engine.
