Fuel Consumption

There are three components used to fully determine the fuel consumption of an internal combustion engine powered vehicle; urban driving, constant 90 kmph and 120 kmph.

The urban simulation is carried out on a chassis dynamometer whereas the constant speed tests can be carried out on the road if necessary. The distance over which these tests are conducted must be at least 2000m on a level road surface (±2%).


Fuel consumption in countries where Imperial units dominate is measured in miles per gallon although the generally accepted method of calculation is in Metric units and is given in terms of litres per 100km.
The gravimetric measurement method is as follows:
C=100*m/(ρ*s) litres/km
where m=mass of fuel consumed (kg), ρ = density of fuel at S.T.P. (kg/litre) and s = distance covered (km).

The volumetric measurement is as follows:
Vplumetric measurement
where V = volume of fuel consumed (kg), α = thermal expansion coefficient of fuel and t = fuel temperature in °C and s = distance covered (km).
A correction multiplier of 1.1 is used to compensate for resistive forces encountered on normal road use (as opposed to those encounterd on a chassis dynamometer). This correction factor is calculated as follows:

equation
Conversions
1 mile per gallon (UK)=0.425 kml-1 1 mpg (UK)=282.4809363 litres per 100km
1 miles/gallon(US)=1.2009499 miles/gallon(UK) 1 mpg (US)=235.2145833 litres per 100km

Enter one distance and one fuel consumed value to calculate or just one fuel consumption value to convert.

See also: Brake Specific Fuel Consumption, Engine Tuning to Reduce Fuel Consumption, Gallon, Miles Per Gallon Equivalent, Specific Fuel Consumption.

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Subjects: Automotive Engines


Weblinks:
VCAcarfueldata.org.uk New Car Fuel Consumption and Exhaust Emissions Figures.