With increasing concern on energy security and energy efficiency, automobile industry has been conducting many research on technologies aimed at reducing weight and reducing fuel consumption thereby reducing carbon footprint of the vehicle without compromising safety, efficiency and operational ability. Alternative fuel vehicles such as Compressed Natural Gas (CNG), Liquefied Petroleum Gas (LPG), Hydrogen, Hydrogen-CNG (HCNG) blends and Liquefied Natural Gas (LNG) vehicles are some of the best solutions to minimize the dependence on fossil fuels which are depleting fast. Gas cylinders are the heavier portion of alternative fuel systems which adds more weight to vehicle unladen weight. In search of innovative materials for gas cylinders, composite materials have been the front runner in reducing weight of the vehicle, thereby reducing fuel consumption significantly. This paper describes the various types of composite gas cylinders, their design and test requirements, merits and demerits of each type of composite cylinder. Current status of adoption of composite cylinder technology in India and worldwide, such as number of composite cylinder manufacturers in world, level of introduction of composite cylinders in different types of vehicles and incidents happened due to composite cylinders are also described in this paper. Based on review of composite cylinder technology, it is concluded that allcomposite cylinder technology (i.e., Type-4 cylinders) is the best solution for light weighting of automotive heavy duty commercial vehicles such as buses without compromising on safety.