Theoretical investigation with reasoning of petrol fuel combustion in the ambient and ozone medium was made. Methods of carrying out the experiment using the engine loading method due to application of power of mechanical losses of deactivated cylinders were worked out. Experimental studies envisage determination of influence of ozone additive into fuel air mix on the basic effective ICE performance, for this purpose cyclic fuel consumption parameter was used. After the analysis of ICE performance methods and control techniques, its condition was evaluated, for this purpose a compressor meter was used with preliminary pressurization of cylinders. During the experiment in order to load the engine its third and fourth cylinders were switched off. The results showed that the utmost fuel efficiency is found at crankshaft rotation values of 1450 and 3350 min-1, when cyclic fuel consumption rate has values of 1,35 and 1,27 mg/cycle respectively, which makes 7,4 and 7,0 % from identical indicators without ozonation of air mass at the same rotations. In general, the effect of fuel air mix ozonation makes it possible to develop target petrol-operated engine rotations at smaller fuel consumption rate, this way increasing its energy efficiency.