What is Car MPG and How is it Calculated?

For prospective car buyers, understanding a vehicle's fuel efficiency (or MPG as it’s usually referred to) should be an important factor in their buying decision. After all, MPG (miles per gallon) plays a big role in how expensive a car will be to run, not to mention its environmental impact.

In this article, we aim to demist MPG, breaking down exactly what car MPG is and simplifying how it’s calculated. We also share what’s considered ‘good’ MPG and share some of our top recommended models, known for their impressive fuel efficiency.

What is car MPG?

Simply put, MPG (Miles Per Gallon) is the measurement of how far a car can travel on a single gallon of fuel. This acts as a gauge of how fuel efficient a vehicle is - the higher the number of miles it can do per gallon, the better the fuel efficiency.

If we compare two cars as an example:

Car A has an MPG of 50

Car B has an MPG of 60

If you were looking at running costs when buying either Car A or Car B, you would likely opt for Car B since you can travel 10 more miles per gallon of fuel, compared to Car A.

A higher MPG also has the benefit that it can lessen the car’s environmental impact, since it requires less fuel to burn.

How is car MPG calculated?

The MPG of a car is determined through the Worldwide Harmonised Light Vehicle Test Procedure (WLTP), which is essentially a series of standardised tests carried out in a lab. These tests simulate various driving conditions & use variables such as weight, rolling resistance and aerodynamics, in order to provide a fair comparison of fuel consumption between different vehicle models.

The WLTP test consists of four different driving cycles, each representing a specific driving scenario. To determine the MPG value, the covered distance in the four test cycles below is divided by the fuel used, giving us the number of miles a car can travel per gallon, under the simulated conditions.


This cycle simulates urban driving conditions with lower speeds, frequent stops, and acceleration.


This cycle represents a mix of urban & extra-urban driving, including moderate speeds & varied traffic conditions.


This cycle simulates driving on highways or motorways, with higher speeds and less stop-and-go traffic.


This cycle represents more aggressive driving conditions, including higher speeds and rapid acceleration.

During each of the above tests, the vehicle's fuel consumption and emissions are measured using highly accurate equipment, providing data on carbon dioxide (CO2) emissions, as well as other pollutants.

Combined MPG is generally the figure you will see used to by car manufacturers. It is calculated using a combination of urban and extra-urban driving conditions thus giving the most accurate measure for the majority of drivers who use their cars for both commuting and pleasure.

Even with the best tech in the World, it is still extremely challenging to replicate every day conditions such as wind direction or even the weight carried, which is why you will often find the MPG your car achieves will differ to the official MPG figures, as everyone has their own driving style and as driving conditions are constantly changing.


What is the average MPG for a car?

As we’ve already alluded to, the average MPG for a car can vary significantly, depending on factors such as vehicle size, type, engine specifications, and driving conditions.

Petrol-powered cars generally achieve average MPG figures ranging from 35 to 45 miles per gallon, while diesel-powered cars tend to exhibit higher averages of around 40 to 60 miles per gallon.

In the UK specifically, the latest data suggests that petrol cars have an average MPG of 36, whilst diesel cars get an average of 43 MPG. In comparison, the average MPG of an electric car in the UK is significantly higher, at 132 MPG.

What would class as ‘good’ MPG?

Based on the averages described above, we’d recommend that anything above 40 MPG for a petrol car would constitute as being good (and anything above 50 MPG for a diesel car). If you’re looking for real value per mile, anything above 50 MPG for petrol and 60 MPG for a diesel car would be impressive.

Top Cars for Good MPG: Suzuki Swace and Suzuki S-Cross

When it comes to fuel-efficient cars, Suzuki offers notable options that prioritise excellent MPG ratings, without compromising performance or style.

Two models worth considering due to their good MPG ratings are the Suzuki Swace and Suzuki S-Cross.

Suzuki S-Cross 

The mild-hybrid 1.4 litre version has a combined MPG figure of 53.2, whilst the 1.5 litre full-hybrid option offers an impressive 54.3 miles per gallon.

The S-Cross is an SUV similar in size to a Nissan Qashqai or Kia Sportage & is the perfect choice for those who are looking for a great value car for the family with an added option of Suzuki's ALLGRIP 4x4 to keep you on the road no matter what the weather.

Take a closer look at the S-Cross.

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Suzuki Swace

The full-hybrid 1.8 litre Swace is definitely the choice for those who are looking to get more from each tank of fuel with a combined MPG of 62.7 which will last over a whopping 600 miles!

The Swace was born from a collaboration between Suzuki & Toyota & is a fully-loaded estate which comes with all the spec & tech you could ever need & plenty of space for everyone & everything.

Take a closer look at the Swace.

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Explore the 100% Hybrid Suzuki Range at Colin Appleyard

If MPG is something you're looking for in your next car, then the Suzuki line-up is definitely worthy of consideration offering 100% hybrid & ranging from compact mild & full hybrid cars & SUVs to the option of a plug-in hybrid offering an outstanding 282 miles per gallon! And as the longest serving Suzuki dealer in the UK, you'll be in safe hands with our expert team to guide you through all the options to find the car which is best suited for you.

Contact our Suzuki team today to find out more & to experience the Suzuki range.