A Quick Guide on How to Calculate Fuel Consumption of a Car

calculation of fuel consumption — (Source: hswstatic)

If you are a car owner, you must be aware of the rising fuel cost. This makes it more difficult to support car maintenance financially. In this regard, it can be helpful to have an idea of the fuel consumption level of your vehicle. It can further help you plan and reduce your expenses.

Are you curious to learn how to calculate fuel consumption? You will find all the details about the same in this piece.

What Is Fuel Consumption of a Car?

The term fuel consumption mainly measures the amount of fuel a car consumes while travelling a certain distance. Usually, it is expressed through litres per 100 kilometres. If the fuel consumption is high, your expenses for maintaining the vehicle will also start rising.

The entire amount is not used to cater to a car's energy. The rolling assistance of a vehicle consumes about 3-11% of the fuel. Moreover, driving methods can also help to reduce fuel consumption.

How to Calculate Fuel Consumption?

The process of calculating fuel consumption can be a complex one. However, it is necessary to keep track of the fuel you are feeding your car to manage the expenses. Here are three ways you can do it.

Method 1: Based on Distance Covered

If you are willing to learn the procedure of calculating fuel consumption per km, this method can help you out. Divide the amount of gas used by the distance covered. You can get this information by tracking the odometer every 100 km.

The following fuel consumption formula can be useful here.

(Litres used X 100) / km travelled = Litres per 100 km

Method 2: Resetting the "Trip Odometer"

Cars these days come with a trip odometer as a small button on the dashboard or centre console. It has an option of resetting to zero anytime the rider wants. Every time you refill the vehicle with gas, reset the odometer to zero and keep checking the consumption based on your travel distance. If you do not have a trip odometer, you can record the starting mileage to track this consumption.

Method 3: Based on the Final Mileage

With this method, you can record the mileage on your odometer as the final mileage. It would help if you did this before filling up the vehicle from a gas station. The difference between the starting mileage and current mileage will also give you this information if your car does not have an odometer.

What Are the Factors Affecting Fuel Consumption of a Car?

There can be multiple factors affecting fuel consumption. Knowing about these will help you control them and reduce your consumption in future. The following list will be helpful in this regard.

1. Vehicle Size and Weight

Your car's weight is a major factor influencing its fuel consumption. The weight indicates the energy your car needs for moving, which, in turn, indicates the amount of fuel required. The size of the vehicle also has a part to play in this regard.

For instance, a compact vehicle weighs less than a truck or SUV. Moreover, it can have a smaller engine and work with less fuel and energy. If two vehicles are of the same size, the components and materials will determine the fuel consumption.

2. Vehicle Displacement

Displacement refers to the volume of air a car’s engine consumes in a single revolution. The more air it needs in this process, the higher will be the requirement for energy. The measurement of displacement is expressed in litres. Naturally, higher displacement will consume higher fuel.

3. Mechanical Resistance

Every vehicle has its own set of mechanical resistance. It determines the amount of energy a vehicle requires o move all the parts of its drivetrain. Components like the transmission, wheel bearings, axels and others contribute to the motion of a car.

While putting these together, engineers can refine the system to minimise the power required for the parts to come in motion. For instance, manual transmission requires less energy than automatic. This can influence fuel consumption.

4. Aerodynamic Efficiency

Air poses resistance when a car is trying to move. Having curves and well-designed shapes can help cars avoid this resistance. For instance, trucks have few curves. Naturally, they require more fuel to move. Thus, car exteriors with more curves and unique designs can help reduce fuel consumption.

What Are the Reasons for Overconsumption of Fuel?

Now that you know the factors affecting a car's fuel consumption, you must be curious to know about the reasons for excess fuel consumption. The following list will be beneficial in this regard.

Excessive short trips: A car engine works best when it is warm. However, the engine does not get the time to warm up properly when you use your car for multiple short trips. Naturally, it is consuming more fuel than usual.
Heavy acceleration and braking: Your driving behaviour can also influence fuel consumption. Aggressive and rash driving can result in overconsumption of fuel. If you apply heavy brakes and acceleration, the fuel economy will drop rapidly.
Cold weather: If you frequently drive in extremely cold weather, your car's engine will take a long time to warm up. It cannot develop the right temperature for getting the energy. This will reduce the fuel efficiency of a vehicle.
Speeding: Another factor behind fuel overconsumption is speeding. If you are used to driving over the speed of 80 kmph, your car will use more gas quickly. However, it helps to create higher air resistance, decreasing fuel economy.
Faulty engine: If you fail to replace worn-out air cleaner elements, spark plugs, or fuel filters while driving a car with a petrol engine, the engine will become faulty. Dirty fuel injectors and air cleaner elements in a diesel engine can cause similar issues. This situation can increase fuel consumption.
Poor engine oil: The quality engine oil can also be a major reason behind the increased fuel requirement of your vehicle. If your engine oil is thicker than recommended, you are using the wrong motor oil viscosity grade. This adds a load to the engine, increasing fuel consumption.
Tyre quality and maintenance: The proper maintenance of a vehicle is mandatory if you are trying to reduce its fuel consumption. If the tyres are worn out, they will spin faster, taking a toll on your fuel economy.
Gear and clutch issues: If you are in gear lower than the current requirement are likely to waste more fuel. Thus, knowing the right gear is important. Additionally, a worn-out clutch causes tyre slippage, indicating insufficient contact between the clutch and pressure plate.

How to Prevent Overconsumption of Fuel?

As you can see, multiple reasons can contribute to excessive fuel consumption. Here are some tips that can help you prevent overconsumption and control expenses.

Maintain steady acceleration and braking: While driving, avoid being too harsh in applying brake or accelerating. Maintain steady braking by keeping your foot on the brake pedal. This way, you can avoid hard braking and thereby reduce fuel consumption.
Avoid idling and short trips: If your car is running but not moving, you constantly lose fuel. Hence, avoid idling and switch off the engine if you are not driving. Moreover, avoiding short trips will help you avoid draining the car battery and energy of the engine, requiring higher fuel.
Use cruise control on highways: To maintain a constant velocity, you must use cruise control. It reduces the pressure on the engine, and the car requires less gas and fuel to run.
Lower the drag: If you are driving across the down with a roof box or cargo carrier, there are chances that you are cutting into your fuel economy with unnecessary drag. Avoiding these unnecessary accessories will help you avoid fuel consumption.
Maintain the car AC: It is advisable to drive with the car AC, as open windows can cause wind resistance. However, the AC temperature should be moderate and not too high. This way, you can control your car’s fuel requirements.
Maintain tyre inflation: Underinflated tyres have higher rolling resistance, which reduces fuel efficiency. Therefore, it is advisable to maintain tyre inflation. You can use a pressure gauge to monitor the tyre pressure. This way, you can take measures if your tyres are underinflated.
Avoid putting a load in the vehicle: Check the load index of your car and tyres, and keep items accordingly. Try to remove any necessary items from your car or its trunk. If your car is light, there will be minimal pressure on the engines, reducing fuel consumption.

Hopefully, now you know how to calculate fuel consumption. It is an important step to avoid making any serious mistakes while driving, as it can take a toll on your car maintenance expenses. If you follow the tips suggested in this article, you can avoid excess fuel consumption.

Frequently Asked Questions

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What determines the fuel efficiency of a vehicle?

Fuel efficiency or the fuel density is expressed as a quantitative value. If there is high energy in fuel for every unit of volume, the car has high fuel efficiency.

How does engine size affect fuel consumption?

An engine larger in size is likely to burn more fuel, as per each revolution, it turns in a minute (RPM). A smaller engine with lower RPM will consume lesser fuel while covering the same distance.