Requirements regarding high fuel efficiency, low pollutants and CO2 emission impact of the internal combustion (IC) engine results in high control calibration complexity. Modern IC engines are equipped with numerous electronically controlled subsystems, whose usage leads to almost exponential growth of stationary operating points that need to be evaluated and optimised. In that perspective, the methodology for fast pre-knowledge acquisition of examined system is presented through the application of Slow Dynamic Slope experiments – SDS. Continual slow change of a control parameter excites the system, in such a way, that allow obtaining of an approximately stationary operating regime, without the time-consuming operating point settling period. By analysing stationary-based approximation results of Slow Dynamic Slope experiments, conducted within the IC engine global operation domain (engine speed and load), certain zones could be identified. Within those zones, increased number of stationary tests is desirable in order to provide a more precise approximative model of observed engine output parameters. In this way, relatively fast dynamic SDS experiments could be used to optimise the stationary-based test plan leading to overall time savings dedicated to IC engine testing.