. "2 Vehicle Fundamentals, Fuel Consumption, and Emissions." Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles. Washington, DC: The National Academies Press, 2010.
U.S. Environmental Protection Agency (EPA) city-highway dynamometer test procedures.1
The terms fuel economy and fuel consumption are both used to show the efficiency of how fuel is used in vehicles. These terms need to be defined.
Fuel economy is a measure of how far a vehicle will go with a gallon of fuel and is expressed in miles per gallon (mpg). This is the term used by consumers, manufacturers, and regulators to communicate with the public in North America.
Fuel consumption is the inverse measure—the amount of fuel consumed in driving a given distance—and is measured in units such as gallons per 100 miles or liters per kilometer. Fuel consumption is a fundamental engineering measure and is useful because it is related directly to the goal of decreasing the amount of fuel required to travel a given distance.
A dynamometer is a machine used to simulate the forces on a drive train to test pollutant emissions, fuel consumption, and other operating characteristics of a vehicle or an engine under controlled and repeatable circumstances.