: Gasoline compression ignition(GCI) is a concept that utilizes gasoline instead of diesel in a CI engine for higher efficiency and lower emissions. In this study, experimental and numerical approaches were used to understand the spray and combustion characteristics of gasoline in a heavy-duty CI engine under a low-load condition. Using spray and flame images, GCI was compared with diesel CI in terms of combustion phasing, ignition delay, engine power, and emissions. The distributions of the vapor phases and OH radicals were calculated to investigate the GCI characteristics. The predicted equivalence ratio and combustion temperature were used to plot the operating point on the phi-T map. As a result, it was found that gasoline is more suitable for a lean and well-distributed mixture inside the cylinder due to its high volatility and high resistance to autoignition. Only the premixed flame of GCI was an evidence of low-soot emission. GCI was operating in the region of advanced combustion technologies on the phi-T map.