If you're anything like us, you'll not be visiting the local motoring websites but you'll be exploring sites from across the globe. Looking at new releases and reading (or watching) reviews from international motoring outlets will see you encounter terms that may be a little confusing and strange. The USA loves working in the Imperial system while the UK is a strange one that combines both Imperial and Metric units. In South Africa, we work in Metric units only.
Related: What is Fuel consumption (average)? How is it calculated?
In an American publication, you'll read about horsepower (HP), miles, mpg, and pound-feet of torque (lb/ft). The UK will also use miles and horsepower but even though it sounds as if they match the United States when it comes to measurements, there is one slight difference. Both of these territories also employ the 'gallon' as a unit of fluid measurement. Think of it as their version of a 'litre' even if the quantity isn't the same as a litre.
How much is a gallon?
Here's where the tricky bit comes in. The UK uses the Imperial gallon while the USA uses their own version and the two are not the same. Here's how they convert to litres.
1 UK Imperial Gallon = 4.546-litres
1 US gallon = 3.785-litres
So it's easy to see that there's quite a variance but how does that affect the figures that you're reading?
What is MPG?
In short, MPG is Miles Per Gallon and is usually written as mpg. This is a calculation of how many miles (the distance) a vehicle can travel on 1 gallon of fuel. Seeing as the gallon measurement differs between US and UK territories, this figure will be different depending on what publication you are reading.
The South African equivalent used to be kilometres per litre or km/l but in more recent years this has changed to litres per 100km, how much fuel a vehicle uses for ever 100km it travels. The reason for switching from km/l to l/100km is to make it easier to assess whether a vehicle is economical or not. In both mpg and km/l, the higher the number the better the fuel consumption. This can be confusing.
That's why we use l/100km now, the lower the number, the better the fuel consumption - it just makes logical sense.
How do I convert it?
Let's look at what 1mpg means to you in both US and UK formats and how they can be reversed. If you're not keen to do the match yourself then head on over to this calculator that will allow you to input the numbers for a quick conversion.
| US mpg | UK mpg | km/l | l/100km |
| 1 | 1.20095 | 0.42514 | 235.2145 |
| 0.832674 | 1 | 0.354 | 282.481 |
| 2.352145 | 2.82481 | 1 | 100 |
| 235.2145 | 282.481 | 100 | 1 |
