Diesel or Petrol? Which is the right choice for you?

Diesel or Petrol? Which is the right choice for you?

We understand there are many choices you will have to make when it comes to buying a car. From what colour car you like, to how many doors would be suitable, what size boot do you need and so on. What type of fuel your vehicle runs off could be one the of the most important depending on your driving circumstances.

What are the main differences between diesel and petrol cars?

The difference between petrol and diesel is found in the way that the combustion occurs. A petrol engine blends fuel with air before being ignited by spark plugs, in a diesel engine the air is compressed and then the fuel is injected.

Which is cheaper petrol or diesel?

Purchase price

The initial purchase makes a diesel more expensive. Diesel cars generally cost more than petrol equivalents because modern diesel cars are fitted with complex technology that reduces their particulate emissions.

Fuel costs

At the moment diesel is more expensive compared with petrol at the pumps. As of November 2022, diesel is around £1.86 per litre and petrol is around £1.63 per litre.

While unleaded petrol tends to be less expensive at the pumps per litre than diesel, cars using diesel are known for being more efficient with fuel use. Making diesel-powered cars are a more budget-friendly choice in the long term.

Maintenance costs

The cost of maintenance and repairs will differ based on the make and model of a car, and how many miles the car is being driven each year.

Repairs cost less on petrol cars, but the engine can experience more difficulties over time. If you want to have the vehicle for a long time, then a diesel may be a better option.

A trip to the local garage with your diesel vehicle may cost a little more, but you shouldn’t be needing to take it to the garage as often as a petrol.

Is diesel or petrol better for the environment?

Diesel engines emit less CO2 and greenhouse gases compared with petrol engines. This is because of the particular type of fuel and the internal efficiency of the diesel engine.

The fuel used in diesel engines has a higher compression ratio than petrol and it also functions better than petrol engines. As a result, less fuel is used to travel the same distance.

Most approximations suggest that diesel engines produce about 10% less than the petrol engines of the same category.

Petrol or diesel for short journeys?

For shorter journeys like to and from the shops, driving around town or if you have a shorter or slower-paced commute, a petrol engine will be the most suitable compared with diesel. Diesel is going to better for longer journeys because of its increased fuel economy.

The diesel particulate filter (DPF) on modern diesels, which traps soot particles in the exhaust, would also be a problem if you are only doing short journeys. Every now and again the soot must be burnt off to prevent filter blockage, and the DPF has to get very hot to do this. To do this you would need to drive the vehicle over 50mph or more for more than 30 minutes.

Also, if you generally do shorter journeys, your motoring requirements also suit hybrid and electric cars, which, despite being pricier to buy, can have much lower running costs so could be a good option as well.

Pros and cons of petrol cars


  • Their engines are generally quieter than diesel vehicles.
  • Cheaper upfront costs than similar diesel models.
  • Cheaper fuel at the pumps compared with diesel.


  • are less efficient so use up more fuel.
  • Higher CO2 emissions by 20% so you must pay more in car tax in the first year, but then the standard £140 a year will apply.
  • They tend to depreciate faster.

Pros and cons of diesel cars


  • A diesel car uses less fuel. It is estimated you could save as much as 30% throughout the year, purchasing significantly lower amounts of fuel than your typical petrol car.
  • Cheaper car tax. As diesel cars have lower CO2 emissions, you should expect to pay less in car tax for the first year with your vehicle. However, after this, you will need to pay the standard £140.
  • Maintenance of the vehicle. You’ll find that a diesel engine will last longer compared to the typical petrol car.
  • Diesel cars depreciate on the market at a lower rate.


  • Diesel vehicles especially older ones can be noisier compared with petrol.
  • As mentioned above diesel fuel costs more at the pumps so filling up will be more costly for you.
  • If you don’t drive on motorways regularly your diesel particulate filter (DPF) could get clogged up and this can be expensive as a garage will need to clear this out for you.
  • Higher initial price when purchasing a diesel car compared with petrol.

What about the future?

All new petrol and diesel cars and vans are set to be banned from sale in the UK in 2030. New hybrids will be given until 2035, on the condition they can cover a “significant distance” in zero-emission mode.

After 2035, the only new cars and vans that can be sold will be absolute electric ones, plus any hydrogen-powered cars, that may exist. Second-hand cars will be unaffected by the ban.

Frequently asked questions

Take a look at the below frequently asked questions to help you become more knowledgeable when it comes to making a decision on purchasing a petrol or a diesel vehicle:

Is e10 petrol or diesel?

E10 is the standard grade petrol available at almost all petrol stations the UK.

Is e5 petrol or diesel?

E5 is a petrol that is being replaced by E10 at UK fuel stations. E5 is octane petrol with no more than 5% renewable ethanol, hence the name E5.

New vehicles manufactured from 2019 onwards should have an ‘E10’ and ‘E5’ label close to the filler cap showing what fuel you should use. If your vehicle or equipment doesn’t have this label, you can check their compatibility by checking your manual or contact the vehicle manufacturer.

How to tell if you have a petrol or a diesel car?

You usually can tell from the sound of the car. The engine in diesel cars produces a distinct tractor-like sound compared to the smoother noise of their petrol alternatives.

When it comes to filling up your car. The diesel nozzle is larger than the petrol one so will often not fit in petrol cars.

Sometimes you can tell from the car model. The vehicles with a diesel engine are likely to have the letter ‘D’ in the model’s name. For example, BMW 320d, here the ‘D’ indicates that these cars have a diesel engine.

You can check the car details online with website such as www.checkcardetails.co.uk