Operating method of a hybrid heat-air engine and suitable engine

The method involves operating a set of cylinders (1) in a mode e.g. thermal mode, and determining a current load to be produced by an engine by a logic controller. The current load is distributed between cylinders during a specific time period, so that each cylinder in the thermal mode is sensitive to optimal load at cycles when a thermal mode is implemented for achieving production of load, where the optimal load for the cylinder in thermal mode is a load providing maximal output of the cylinder and average load produced in conditions is equal to the current load to be produced. An independent claim is also included for a thermal-pneumatic hybrid engine of a motor vehicle, comprising a set of cylinders.