Editing Fuel efficiency (section)

{{short description|Form of thermal efficiency}}
{{Public Infrastructure}}

'''Fuel efficiency''' (or '''fuel economy''') is a form of [[thermal efficiency]], meaning the [[ratio]] of effort to result of a process that converts [[chemical energy|chemical]] [[potential energy]] contained in a carrier ([[fuel]]) into kinetic energy or [[Mechanical work|work]]. Overall fuel efficiency may vary per device, which in turn may vary per application, and this spectrum of variance is often illustrated as a continuous [[energy profile]]. Non-transportation applications, such as [[Industrial sector|industry]], benefit from increased fuel efficiency, especially [[fossil fuel power plant]]s or industries dealing with [[combustion]], such as [[ammonia]] production during the [[Haber process]].

In the context of [[transport]], fuel economy is the [[energy efficiency in transportation|energy efficiency]] of a particular vehicle,  given as a [[ratio]] of distance traveled per unit of [[Motor fuel|fuel]] consumed. It is dependent on several factors  including [[engine efficiency]], [[transmission (mechanics)|transmission]] design, and [[tire]] design. In most countries, using the [[metric system]], fuel economy is stated as "fuel consumption" in [[liter]]s per 100 [[kilometers]] (L/100&nbsp;km) or kilometers per liter (km/L or kmpl). In a number of countries still using other systems, fuel economy is expressed in [[mile]]s per [[gallon]] (mpg), for example in the US and usually also in the UK ([[Imperial units|imperial]] gallon); there is sometimes confusion as the imperial gallon is 20% larger than the US gallon so that mpg values are not directly comparable.  Traditionally, litres per [[Scandinavian mile|mil]] were used in [[Norway]] and [[Sweden]], but both have aligned to the EU standard of L/100&nbsp;km. <ref>{{cite web|url=http://www.bilsweden.se/miljo-sakerhet/miljo/information-gallande-bransleforbrukning-for-nya-bilar|access-date=7 November 2019|title=Information on the fuel consumption of new cars|archive-date=8 September 2019|archive-url=https://web.archive.org/web/20190908124154/http://www.bilsweden.se/miljo-sakerhet/miljo/information-gallande-bransleforbrukning-for-nya-bilar|url-status=dead}}</ref>

Fuel consumption is a more accurate measure of a vehicle's performance because it is a linear relationship while fuel economy leads to distortions in efficiency improvements.<ref>{{cite web |url= http://www.fueleconomy.gov/feg/label/learn-more-gasoline-label.shtml#fuel-consumption-rate |title= Learn More About the Fuel Economy Label for Gasoline Vehicles |url-status= live |archive-url= https://web.archive.org/web/20130705143242/http://www.fueleconomy.gov/feg/label/learn-more-gasoline-label.shtml#fuel-consumption-rate |archive-date= 2013-07-05 }}</ref> Weight-specific efficiency (efficiency per unit weight) may be stated for [[freight]], and passenger-specific efficiency (vehicle efficiency per passenger) for passenger vehicles.