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Fuel Efficiency and How to Calculate It!

Last updated date: 17th Apr 2024
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An Introduction to Fuel Efficiency

Fuel is mainly a substance that on burning produces heat or power. Materials like coal, wood, oil, or gas provide heat once burned. Methanol, gasoline, diesel, propane, and fossil fuel, are also different forms of fuel. The efficiency with which the heat produced by fuel is converted to mechanical energy is known as fuel efficiency.

Using fuel efficiency or fuel economy, we are able to measure how long a vehicle can travel. It is the opposite of fuel consumption. Fuel efficiency is measured in km L-1. The fuel efficiency formula, and fuel efficiency range will be discussed. We will also define fuel efficiency and some fuel information.

What is Fuel?

Fuel is considered to be a substance that produces heat and energy once it's burned. The energy that's released throughout the burning process is usually in the form of chemical energy or heat or it's an exothermic method.

What is fuel?

What is Fuel?

The heat released by burning fuels is used for various functions like cooking, heating, and for several industrial and manufacturing purposes. For example, an engine is used to convert heat into mechanical energy when we use fuel to run our cars. The oil that is used as fuel in the engine is known as fuel oil.

Fuel Efficiency

What is fuel efficiency? Energy can't be created or destroyed. Energy can only be transferred. Fuel additionally does not produce energy. The chemical energy present in the fuel is converted to different forms of energy such as mechanical energy with the help of either the thermal or electrical energy provided to it. The efficiency with which the fuel undergoes this conversion of energy is known as fuel efficiency.

Fuel efficiency refers to a measure of what distance an automobile can cover with a particular volume of fuel. Few factors have an effect on the fuel efficiency of a vehicle. When the maintenance of the vehicle is neglected, all of the systems, as well as those directly associated with fuel efficiency, run less efficiently. For example, a blocked air filter might have an effect on engine performance and as a result, a lot of fuel is consumed. Calorific value, weather, and engine performance have an effect on the fuel efficiency value.

Importance of Fuel Efficiency

Vehicles with higher fuel efficiency tend to consume less fuel to carry out the same task. Therefore, for reducing the wastage of fuel, selecting a fuel-efficient vehicle will bring a good range of advantages: reducing carbon footprint, cutting our dependence on oil, saving fuel prices, etc. Let's take a quick look at the advantages of fuel efficiency.

  • Reduces Carbon Footprint: A recent study found that driving a more fuel-efficient vehicle is the most realistic and effective action to attain the biggest cuts in emissions.

  • Saves Money on Gas: If you begin trying to drive a more fuel-efficient automobile and use less fuel, not only can you save money, but you'll be able to spend that saved money on something more significant to you instead.

Difference Between Fuel Economy and Fuel Consumption

Fuel consumption describes what proportion of fuel in an automobile is consumed to cover an actual distance and fuel economy measures how much distance an automobile gets out of fuel. Although the meanings are similar, there's a small difference between them.

  • Fuel Consumption: It measures the quantity of fuel an automobile consumes to travel a particular distance. It's expressed in L/100km. The smaller the value, the higher the rating of the vehicle.

  • Fuel Economy: This measures how far an automobile will go using a set amount of fuel. Its unit is miles per gallon (MPG) or kilojoules per kg (KPK). This is often the inverse of fuel consumption, the larger the value, the higher the rating.

How to Calculate Fuel Efficiency

As gas prices rise, fuel efficiency is changing into more of a critical issue. The steps for calculating fuel efficiency are as follows:

  • Go to the petrol station and fill up the fuel tank.

  • Record the mileage as mileage A.

  • To get an accurate reading, drive till the tank is less than half full.

  • Try to use the same station using the same pump because of the initial fill-up, as pumps may be differently calibrated. This time, take care of the number of gallons it takes to fill up the tank. This can be typically shown at the pump.

  • Re-record the mileage. This range will be marked as Mileage B.

  • The formula for determining the MPG value is :

$\frac{\text{Mileage B - Mileage A}}{\text{Gallons}}\text{=MPG}\left( \text{Miles Per Gallon} \right)$

Subtract Mileage A from Mileage B. This may provide you with the number of miles you drove since your last fill-up. Divide your answer by the number of gallons (Gallons B) it took to fill up your tank. This may provide you with your car's MPG.

Interesting Facts About Boosting Fuel Efficiency

Some tips to boost fuel efficiency are as follows:

  • Drive steady at the proposed speed limit.

  • Avoid the idleness of your vehicle each summer and winter as it produces excess greenhouse gases.

  • Lighten your load and maintain the tire pressure.

  • Schedule regular maintenance for your vehicle.

  • Fuel savers, generally, reduce the car’s fuel consumption.


Fuel efficiency is measured as the quantity of heat released by consuming one kg of fuel (any fuel) on combustion. The unit of measurement of fuel efficiency is kilojoules per kg, i.e. kJ/kg or miles per gallon (MPG). The overall fuel efficiency of the vehicle may be increased by a maximum amount of 30 per cent by vehicle maintenance and a focus on the style of driving.

FAQs on Fuel Efficiency and How to Calculate It!

1. What are the factors affecting fuel efficiency?

There are varied factors affecting fuel efficiency like calorific value, variety of vehicle or engine performance, etc. The price and efficiency of fuel are determined by the performance of the engine. For example, bikes are more fuel-efficient than cars. The automobile engine takes a long time to heat up in cold weather. If the engine is cold, it'll take a longer time to start out and if the weather is cold, the method even takes a longer time to start. The higher the calorific value the more economical a fuel will be.

2. What are the characteristics of a good fuel?

The characteristics of excellent fuel are it should have a high calorific value, must be non-polluting, simple to transport, easily accessible, and should have a moderate ignition temperature. Any substance that's burned to provide heat and release energy is known as fuel. Once the fuel is burnt, the energy stored in it is converted into another form. There are different kinds of fuel. It may be in any state i.e. solid, liquid or gaseous.

3. What's the difference between MPG and MPGe?

While MPG is used for miles per gallon, MPGe has started developing more recently with the arrival of electric cars. MPGe means miles per gallon equivalent and could be a way to offer customers a concept of what kind of mileage they're going to get from a full charge of their electric vehicle. It measures the fuel efficiency of vehicles that run on non-liquid fuels, like hybrid and electrical models. These fuels, like gas, fossil fuel, and electricity, are rated in MPGe as against the quality miles-per-gallon.