LPG, Liquefied Petroleum Gas, is a butane-propane mixture obtained in the oil industry as one of the products of oil refining. If you subject this fuel to pressure it becomes a liquid and can easily be stored in various reservoirs, unlike compressed natural gas or liquefied natural gas that must be cooled or subjected to very high pressures in order to be a stored.
The improvements that this technology brings are cleaner exhaust gases (improvement by at least 10%). With today's technologies there is no loss in performance of vehicles' engines that are remade to run on this type of fuel. It also should not cause increased fuel consumption. All of this, in addition to a much lower price of fuel makes this system very good and economically acceptable.