Is Petrol or Diesel Cheaper?

The answer to that age old question of whether petrol or diesel is cheaper isn’t as clear cut as you probably think it is. In fact, the question’s a lot more complex than a lot of folks first appreciate, tied into the type of engine technology that your car uses, as well as other types of car technology that it uses too.

Here’s why.

Is petrol or diesel cheaper? Well, it depends…

Most people assume that petrol is cheaper than diesel in every respect, full stop. But, at the risk of getting pernickity, that isn’t completely correct. Petrol might indeed be cheaper for some drivers, but it depends on a whole host of changeable factors, like your driving habits, your type of car, your location etc. You might actually find that diesel works out cheaper for you in terms of value for money.


Petrol technically works out cheaper in the short-term. It’s an established fact that petrol is cheaper to buy than diesel in most European countries, (although this varies from place to place – in India, for instance, diesel is actually cheaper). So, if you’re looking for a short-term saving, petrol should be your choice.

But that doesn’t give you great value in terms of MPG.

The drawback of petrol though is that it doesn’t give you great levels of efficiency in terms of miles per gallon. It might be good for the odd trip around town or the short commute each day, but you can’t get many miles out of it – as you’ll know if you’ve ever attempted to drive a petrol car from Bristol to Glasgow (as I have). The simple fact is that you’re going to have to get used to regularly filling up your car if you choose petrol.

Petrol cars are generally cheaper to repair and maintain. Diesels have a habit of being pretty fussy cars to keep working well. Here’s the science.

Petrol cars use sparkplugs to ignite fuel, which then moves a piston and a series of machinery, eventually propelling you forward. Diesel cars however don’t. Instead, air is simply compressed inside the cylinder until the pressure combusts the fuel itself, without the need of being ignited manually. This is a much more powerful form of combustion but it has the effect of increasing general wear and tear on the engine, making diesels more likely to suffer from maintenance problems over time.


Diesel actually works out better in terms of value for money over time, rather than petrol.

Confusingly, you’ll pay more each time you fill up your fuel tank with diesel, but you’ll be able to cover more miles. You’ll usually use around 17% less fuel in a diesel engine rather than a petrol one. This mean that you won’t have to buy diesel as often, helping you get better value for money out of each tank of fuel.

But diesels are more expensive in the short term. Whilst diesel offers better overall fuel efficiency in terms of MPG, it does come at a much larger short-term financial cost when compared with petrol. Diesel is usually more expensive than petrol at the pump, so it’s likely to hit your wallet more every time you fill up.

So is petrol or diesel cheaper?

Whether petrol or diesel works out cheaper or better value for money for you is influenced by a lot of different factors, so you can’t really categorically say that one fuel is better than another.