FuelTheGuide
5 min read Running costs

Petrol or diesel: which costs less to run?

Price per litre is only half of it. What you burn per kilometre decides the rest.

What you'll take away
  • Price per litre alone doesn't tell you which fuel is cheaper to drive.
  • Cost per 100 km, price times consumption, is the number that decides it.
  • Diesel engines usually use less fuel per distance, but not always enough to offset a higher purchase price.
  • The answer depends on your vehicle, your annual distance, and the price gap in your country.
1

Price per litre isn't the whole story

A litre of diesel is often, but not always, cheaper than a litre of petrol at the pump. That fact alone doesn't tell you which fuel costs less to actually drive on, because the two fuels aren't burned at the same rate.

The number that matters is cost per distance, not price per litre.

Cost per 100 km = price per litre × litres used per 100 km

The number that actually decides which fuel is cheaper to run, not the price per litre on its own.

2

How much fuel each one actually uses

Diesel engines usually burn less fuel per kilometre than an equivalent petrol engine, often by a noticeable margin. How much less depends heavily on the vehicle.

Illustrative fuel consumption by vehicle class

Vehicle class
Typical petrol
Typical diesel
Small hatchback
6.0 L/100 km
5.2 L/100 km
Mid-size sedan
7.8 L/100 km
6.0 L/100 km
SUV or van
9.6 L/100 km
7.4 L/100 km
3

Do the math: cost per 100 km

Multiplying price per litre by litres used per 100 km turns two separate numbers into one comparable figure.

Price per litre Cost per 100 km
Petrol
1.58
12.32
Diesel
1.42
8.78

Illustrative example for a mid-size vehicle, not current prices. Diesel is cheaper per litre here, and even more so once actual consumption is factored in.

Run your own numbers

Enter your car's consumption and typical distance to see a cost-per-distance comparison with today's prices.

Open the cost lens
4

What else affects the real cost

Fuel is only one line in the cost of owning and running a car. A full picture includes a few other things too.

Purchase price and depreciation
Diesel vehicles often cost more upfront and hold their value differently depending on the market.
Servicing and repairs
Diesel engines can cost more to service, though this varies a great deal by make and model.
Annual distance
Diesel's advantage grows the more you drive; it can disappear entirely for low-mileage drivers.
Local incentives and restrictions
Some cities restrict or charge extra for older diesel vehicles, which changes the real cost of ownership beyond fuel alone.
5

Common mistakes to avoid

A short list of the errors that most often skew a petrol-versus-diesel comparison.

Comparing price per litre alone Diesel is often, not always, priced below petrol, but that alone doesn't decide which is cheaper to drive.
Using a manufacturer's lab consumption figure as your own Real-world consumption is usually higher than the official test figure, and the gap differs by vehicle and driving style.
Ignoring how much you actually drive The breakeven distance where diesel's fuel savings outweigh a higher purchase price can be many years away for low-mileage drivers, or never reached at all.
Forgetting local taxes and access rules Some cities tax or restrict diesel differently, which can outweigh any saving at the pump.

Questions and answers

Is diesel always cheaper to run than petrol?

No. It depends on the price gap between the two fuels in your country, how much less fuel your specific diesel vehicle uses, and how many kilometres you drive. Run the numbers for your own car rather than assuming.

Why do diesel and petrol prices sometimes flip, with diesel more expensive?

Diesel and petrol come from the same barrel of crude but go through different refining steps. Diesel demand spikes in winter for heating, and excise duty rates differ by fuel type in many countries, so the pump price gap shifts with the season and with policy changes.

Does the comparison change for hybrid or electric vehicles?

Yes, significantly. A plug-in hybrid can run on electricity for short trips and switch to petrol, so the per-kilometre cost depends heavily on how often you charge. A full electric vehicle bypasses the comparison entirely, though electricity pricing and home-charging access add their own variables. The IEA Global EV Outlook covers total cost of ownership comparisons across fuel types in detail.

Terms used in this guide

National average price Weekly change Diesel Excise duty Standard and premium petrol

Keep reading

4 min min · Comparing countries

How to compare fuel prices between countries

Why the same litre isn't the same price: currencies, units, grades and taxes.
7 min min · Price composition

What makes up the price at the pump

Crude oil, refining, distribution and taxes, and why the split differs by country.
6 min min · Policy and subsidies

Why some countries have very cheap fuel

Subsidies, price caps and fixed prices, and what they mean for travellers.