Question

define fuel efficiency

Answer 1

Combustion process which is converted into useful work is called as its fuel efficiency.

Or, in other words, fuel efficiency is the efficiency of a process that converts the chemical potential energy present in the fuel to the useful kinetic energy or work.

For ex:

In case of motor vehicles the fuel efficiency is measured in Kilometer/L.

Answer 2

fuel efficiency is the capacity of an engine, especially that of a vehicle, to obtain energy from fuel.
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