The manual deals with special issues related to the conversion of passenger cars and light trucks equipped with gasoline or diesel internal combustion engines to gas fuel. The appropriateness of switching to gas fuel is justified. The main attention is paid to modern gas cylinder devices of different manufacturers, designed for the conversion of carburetor, diesel engines and engines equipped with an injection system and an electronic control unit. Described are the principle of operation, design features, operating rules and maintenance conditions for various systems of gas equipment.