 Also FCEV does not emit any particulate matter but removes particulate matter up to PM2.5 from the ambient air.Any medium or heavy duty vehicle can be retrofitted in to fuel cell vehicle as its system power density (watts/litre) and system specific power (watts/kg) are comparable with that of internal combustion engine.The cost and durability of fuel cell engines with economies of scale production line are comparable with the petrol/diesel engines.