Currently, the internal combustion engine is facing tough regulations regarding pollution and CO₂. In order to comply with the latest constraints concerning the CO₂ emission, the automotive manufacturers must increase the thermal efficiency of the combustion engine. One way which seems to be preferential for the manufacturers is to implement the Miller over-expanded cycle. One drawback of this cycle is that the flow inside the cylinders is steadier than in the case of the Otto cycle. Consequently, in the present study, in order to understand the air flow phenomena inside the cylinder, a 3D CFD simulation is used. The weight of the study is on the understanding of the internal aerodynamics in the case of the Miller cycle. Finally, solutions to improve the situation were also given.