Being a blog about fuel economy, it’s expected to have a post on how is fuel consumption calculated.
On the other hand, you might be thinking that your goal is to save fuel and not to learn about the whys or calculations.
So why would I want to talk about car fuel consumption calculation? To be honest, in my opinion, I think that’s the first step to improving your fuel economy.
You have to know your fuel economy to improve it. Keep reading and find out why!
Car Fuel Consumption Calculation
There are a large number of reasons for wanting to improve your fuel consumption. Whichever reason you have, you want to improve your fuel economy, I get it.
But for you to know if you’re improving or not you need to compare the figures. If you’re using less fuel for the same distance than you did before, you’re improving.
Virtually any modern car now has its trip computers that will provide fuel consumption figures. If your car is older you need to know how to calculate the fuel consumption. And even if you have a modern car, it’s always good to understand how to determine your fuel economy.
How To Calculate Fuel Consumption Formula
The principle behind calculating your fuel economy is universal and it always relates distance traveled and the fuel consumed on that course.
This is the best way to do it:
- Start by filling up your tank completely;
- Use your car normally until you’ve spent most part of the fuel;
- Fill up your tank again completely;
- Keep track of how much fuel you got in this last fill-up and the distance you covered between the two fillups;
- Now you have to calculate your fuel economy using one of the formulas given below, depending on your region.
The way you apply it might vary depending on where in the world you are:
Liters per 100 kms (l/100kms)
In most of Europe we use liters per 100 kms and so does Canada.
When I fill my fuel tank I read the liters that the pump is putting into my car. My car gauges use km and km/h.
This is how we calculate it:
l/100 kms –> Liters consumed⁄Kms traveledx100
Example: Imagine I traveled 650 kms while consuming 75 liters.
75 liters⁄650 kms x100=11,54 l/100 kms
The lower the result, the more efficient you are.
Kms per liters (km/liter)
Kilometers per liters are used in Japan and Brasil, for instance. It uses the same base units as Europe but in the opposite way.
This is how to calculate it:
Km/liter –> Kms traveled⁄Liters consumed
Example: Imagine I traveled 650 kms while consuming 75 liters.
650 kms⁄75 liters =8,67 kms/liter
The higher the result, the more efficient you are.
Miles Per Gallon (MPG)
Miles Per Gallon, also usually referred to as MPG, simply states how many miles you can drive while consuming a gallon of fuel.
Some of you are probably already guessing that there are two faces to MPG.
Although both the UK and the US use MPG and it might look exactly the same, actually it’s not.
Imperial gallons (UK) and US gallons represent different quantities. A gallon in the UK corresponds to 4.54609 liters but a gallon in the US is only 3.785 liters.
1 UK gallon = 4.54609 liters
1 US gallon = 3.785 liters
Taking liters into consideration, 1 liter corresponds to 0.219969157 UK gallons and 0.264172052 US gallons.
As you might already imagine, that means that the same car will have a higher MPG in the UK than the US. That’s because the UK gallon has more liters of fuel, so you can drive for longer.
That’s just a difference in the calculation as the fuel actually consumed is exactly the same.
Whether you live in the UK or the USA, the way you calculate your MPG is exactly the same:
MPG –> Miles traveled⁄Gallons consumed
Example: let’s say you spent 16,66 gallons to travel 500 miles. You did 30 MPG.
500 miles⁄16,66 gallons=30 MPG
The higher the result, the more efficient you are.