Should I Buy a Petrol or Diesel Car

The debate over which type of fuel is better for propelling the internal combustion engine has been raging for decades. Most buyers will have a preference which is fine, as both engines have their pros and cons.

If you’re undecided, we’re going to run through the basics here, helping you make an informed decision on factors such as performance, reliability and running costs.

What is the Difference Between Diesel and Petrol?

Both types of fuel are derived from exactly the same source, crude oil. The difference is in how each fuel is produced during the refraction process.

Essentially, diesel consists of a thick oily substance which has a much lower burning point whereas petrol has the consistency of water and requires much higher temperatures for it to burn cleanly.

The difference this makes to your car’s engine is in how it operates. Diesel engine cars are not able to rev as highly as their petrol equivalents due to differences in design requirements for each engine. This is because diesel is burnt via compression rather than ignition as you would find in a petrol or gasoline engine.


The ever advancing quest for reduced vehicle emissions has put a strain on both petrol and diesel technology. The use of high pressure fuel pumps and other ancillaries means that neither engine type is as reliable as their far more basic predecessors.

These issues are especially prevalent within diesel engines, particularly with the onset of devices such as EGRs and DPFs which have to be featured in all diesel cars, the sole purpose of which is to further reduce emissions of co2 to keep up with stringent government legislation.

This doesn’t mean that you shouldn’t buy a new diesel car, just that you should go in with your eyes open and read reliability surveys and owner feedback.



This is where it gets interesting. Many diesel owners love the way their cars perform because of the additional torque, or thrust, which is provided by the presence of a turbo charger. Petrol cars on the other hand tend to be much more linear in their performance, requiring plenty of revs on the counter before the engine produces it’s best.

This isn’t to say that diesel cars are faster, only they perform differently and might be suited better to most people’s driving habits.

Running Costs

A diesel engine is always going to result in much higher mpg. Diesel contains far more energy per litre and has a higher caloric value allowing you to travel further for the same amount of fuel. Petrol engines are catching up but are still some way behind.

Take a Test Drive

By now you should have an idea on which type of engine you prefer. We suggest test driving a few different cars and comparing the way they perform. Diesel engines are louder and are considered to be more agricultural, but some people are swayed by the lower running costs. Any car dealer will allow you to take a car out for half an hour or so, so make the most of the opportunity. You are sure to know exactly which type is for you by the time you’re finished.

You might even decide that an electric car is much more suitable for you instead, or how about a hybrid? The best of both worlds.

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