What are the most effective ways to measure fuel efficiency during performance testing?

Fuel efficiency is a key indicator of how well a vehicle performs in terms of environmental impact, operational cost, and regulatory compliance. However, measuring fuel efficiency during performance testing can be challenging, as different methods may yield different results depending on various factors. In this article, you will learn about some of the most effective ways to measure fuel efficiency during performance testing, and what to consider when choosing a method.

1 Fuel consumption rate

One of the most common ways to measure fuel efficiency during performance testing is to calculate the fuel consumption rate (FCR), which is the amount of fuel used per unit of distance or time. FCR can be expressed in liters per 100 kilometers (L/100 km), miles per gallon (mpg), or grams per kilowatt-hour (g/kWh). FCR can be measured directly by using a fuel flow meter, or indirectly by using a mass balance method, which involves weighing the fuel tank before and after the test. FCR can provide a simple and reliable measure of fuel efficiency, but it may not reflect the actual driving conditions or the variations in engine load and speed.

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Kiran Pal🚘🇮🇳

#Automotive/R&D/Fuel System/Wind T/AI-CFD #StayHealthy #Gasoline/Diesel/CNG System Design & Development Professional
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Agree, fuel efficiency can be measured in the form of FCR. In lab FCR can be repeated due to controlled conditions, same times it is difficult in actual due to various factors like fuel quality, vehicle & environment condition etc. Although, FCR can be checked practically by following steps 1. Keep vehicle in standard condition for tire pressure, weight etc 2.Full the tank system till the top level. 2. Driving car on constant speed preferable at 60km/hours 3. Again refill the tank system at same level after drive 4. Measure km run and refill fuel quantity, to know most accurate FCR in actual condition 5. Above method can be used to see the FCR difference due to other factors like outside temp, tire pressure, weight inside vehicle etc

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2 Brake specific fuel consumption

Another way to measure fuel efficiency during performance testing is to calculate the brake specific fuel consumption (BSFC), which is the ratio of fuel flow to brake power output. BSFC can be expressed in grams per kilowatt-hour (g/kWh) or pounds per horsepower-hour (lb/hp-h). BSFC can be measured by using a dynamometer, which is a device that applies a controlled load to the engine and measures its torque and speed. BSFC can provide a more accurate measure of fuel efficiency, as it accounts for the engine efficiency and the power output. However, BSFC may not capture the effects of drivetrain losses, aerodynamic drag, or rolling resistance.

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3 Fuel economy

A third way to measure fuel efficiency during performance testing is to calculate the fuel economy, which is the inverse of fuel consumption rate. Fuel economy can be expressed in kilometers per liter (km/L), miles per gallon (mpg), or watt-hours per kilometer (Wh/km). Fuel economy can be measured by using a fuel flow meter, a mass balance method, or a vehicle simulation software. Fuel economy can provide a more intuitive and relevant measure of fuel efficiency, as it reflects the distance traveled per unit of fuel. However, fuel economy may vary significantly depending on the driving cycle, the vehicle weight, and the ambient conditions.

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Karan Mohan

Global Product Development TRACK Engineer at General Motors | Ex Product Development Intern at Ford Motor Company | EE @ UM-Dearborn
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In my experience working in emissions and certification labs, conducting fuel economy tests for electric vehicles (EVs) can be done by selecting a test schedule such as the Multi-Cycle Test (MCT). During this test, the driver or a robot drives your EV until the battery is fully depleted. Then, you recharge the battery to the state of charge (SOC) it had at the beginning of the test. Next, you measure the power consumed by the test cycle and the power drawn from the wall to charge your vehicle back up.

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4 Carbon dioxide emissions

A fourth way to measure fuel efficiency during performance testing is to calculate the carbon dioxide (CO2) emissions, which are directly proportional to the amount of fuel burned. CO2 emissions can be expressed in grams per kilometer (g/km), grams per mile (g/mi), or kilograms per hour (kg/h). CO2 emissions can be measured by using a gas analyzer, which is a device that samples and analyzes the exhaust gas composition. CO2 emissions can provide a more comprehensive measure of fuel efficiency, as they indicate the environmental impact and the regulatory compliance of the vehicle. However, CO2 emissions may not account for the upstream emissions from the fuel production and distribution.

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5 Specific energy consumption

A fifth way to measure fuel efficiency during performance testing is to calculate the specific energy consumption (SEC), which is the ratio of fuel energy input to vehicle energy output. SEC can be expressed in megajoules per kilometer (MJ/km), megajoules per mile (MJ/mi), or kilowatt-hours per kilometer (kWh/km). SEC can be measured by using a fuel flow meter, a dynamometer, or a vehicle simulation software. SEC can provide a more holistic measure of fuel efficiency, as it incorporates the energy losses from the engine, the drivetrain, and the vehicle. However, SEC may require more complex calculations and assumptions, and may not be easily comparable across different vehicles or fuels.

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6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?

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What are the most effective ways to measure fuel efficiency during performance testing?

1

2

3

4

5

6

1 Fuel consumption rate

2 Brake specific fuel consumption

3 Fuel economy

4 Carbon dioxide emissions

5 Specific energy consumption

6 Here’s what else to consider

Automotive Engineering

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What are the most effective ways to measure fuel efficiency during performance testing?

1

2

3

4

5

6

1 Fuel consumption rate

2 Brake specific fuel consumption

3 Fuel economy

4 Carbon dioxide emissions

5 Specific energy consumption

6 Here’s what else to consider

Automotive Engineering

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