Alternative fuels is a term given to all vehicle propulsion systems that do not use conventional petrol and diesel engines.
It has been used to describe petrol-electric hybrids as well as bi-fuel vehicles that can run on liquefied petroleum gas (LPG) or compressed natural gas, as well as petrol or diesel.
It also encompasses electric vehicles (EVs).
Although LPG-converted cars used to represent a sizeable proportion of the alternative fuels market, their popularity has waned, while petrol-electric hybrids have become more common.
For more on alternative fuels, read the Fleet News guide - The Year of the Electric Vehicle by clicking below.