The article considers the investigation results of the working process of diesel on light fuel. Consumption of natural resources in the form of hydrocarbon fuels, which is steadily increasing in transport, the number of rolling stock, and combustion products of motor fuels cause environmental pollution. It is shown that the transition to cheaper alternative types of fuel, by its characteristics, not inferior to liquid motor fuels, is one of the options to reduce operating costs and harmful emissions. The scheme of classification of gas systems of fuel transfer is presented: by design of the system of filling and storage of gas; by quantity of the substituted basic fuel in the system of fuel supply; by method of dosing of fuel; by name and place of sending of a control signal; by design of the unit of decrease in pressure of gas; by design and a site of heating devices of a gas stream of a high pressure; by a method of ignition of a gas-air mix; by a method of change of indicators of working process; by an aggregate condition of used According to the results of theoretical and operational research of the gas engine based on a supercharged diesel engine: the necessity of using a gas injector power supply system has been established; the power and torque of the gas engine created on the basis of a supercharged diesel engine practically do not differ from that of the diesel engine, which is explained by a relatively high degree of compression for engines with spark ignition (ε=2); it has been shown that in the long term it is possible to use gas supply systems under pressure directly into the engine cylinder. As a result, the most affordable commercial alternative fuel for road transport in Uzbekistan turned out to be natural gas.