In its most basic form, fuel efficiency is defined as a measure of how much a car will convert fuel energy into kinetic energy for travel. In other words, fuel efficiency shows how far your car can travel with a certain amount of fuel. In the United States, the concept is described as miles per gallon (mpg).
fuel economyvaries depending on tire design, transmission structure and vehicle engine, according to Wikipedia and the MIT School of Engineering.
Fuel efficiency measures the effort required to convert the chemical energy of fuel into the kinetic energy your car needs to move. Although the terms fuel economy and fuel efficiency are often used interchangeably, efficiency is a broader term that encompasses how a specific vehicle uses fuel. The latter source points out that both terms are important when developing strategies to reduce greenhouse gas emissions and fuel consumption in the U.S. UU.
There are different ways to measure and discuss the fuel consumption of a vehicle. Fuel efficiency describes the fuel consumption performance of the vehicle. Fuel economy, on the other hand, is a specific number. In the United States, fuel economy is expressed in miles per gallon.
Other countries define fuel economy using different measures, such as kilometers per liter. The UK uses miles per gallon, but the Imperial gallon is larger than the U.S. In its most fundamental form, fuel efficiency refers to a vehicle's ability to extract energy from fuel. The more energy a vehicle can draw from fuel, the more fuel efficiency the vehicle has.
Similarly, the less energy a vehicle draws, the less fuel efficient the vehicle is. Reducing the weight of motor vehicles can also improve efficiency, as heavier cars consume more fuel than lighter cars. Given the calorific value of a fuel, it would be trivial to convert fuel units (such as liters of gasoline) to energy units (such as MJ) and vice versa. Litres per 100 km are also a measure of energy intensity, where the input is measured by the amount of fuel and the output is measured by the distance traveled.
There is a growing community of enthusiasts known as hypermilers who develop and practice driving techniques to increase fuel efficiency and reduce consumption. Non-transportation applications, such as industry, benefit from increased fuel efficiency, especially fossil fuel power plants or industries dealing with combustion, such as ammonia production during the Haber process. Fuel consumption is a more accurate measure of a vehicle's performance because it is a linear relationship, while fuel economy distorts efficiency improvements. The specific energy content of a fuel is the thermal energy obtained when a certain amount (such as a gallon, liter, kilogram) is burned.
Fuel efficiency is a form of thermal efficiency, that is, the relationship between effort and the result of a process that converts the chemical potential energy contained in a vehicle (fuel) into kinetic energy or work. Toyota is testing vehicles powered by hydrogen fuel cells in Southern California, where a series of hydrogen filling stations have been established. In the context of transport, fuel economy is the energy efficiency of a particular vehicle, it is given as a ratio of the distance traveled per unit of fuel consumed. Another reason why many European models are not marketed in the United States is that unions oppose the Big 3 importing any new model built abroad.
For more information, read 'How Is Efficiency Of Fuel Determined?'