In this paper, an experimental investigation is revealed on the solidification process of the latent heat thermal energy storage (LHTES) system, in which the heat energy emitted into the atmosphere with the exhaust gases of ICE vehicles is stored by phase change material (PCM) enhanced with nanoparticles (Al2O3). In the study using RT55 paraffin wax as the PCM, the interior heating process of a typical sedan automobile in cold climate conditions is used as the heat release medium for the LHTES system. Experimental studies carried out in real climatic conditions were repeated for pure paraffin (RT55) and five different Al2O3 fractions (5 wt.%, 10 wt.%, 15 wt.%, 20 wt.%, and 25 wt.%). Experiments are performed in an optical PCM container and are completed after 1200 seconds (20 minutes). The heat energy stored in the PCM container is discharged to the automobile cabin via the closed-circuit liquid circulation system by the heating radiator system in the automobile cabin. The findings showed that the solidification process is improved considerably up to 10 wt.% Al2O3 fractions compared with pure paraffin RT55, and the temperature in the cabin could be increased by approximately 29%. In addition, the Al2O3 fraction increased by more than 10 wt.%, which has a negative effect on the improvement in the solidification process, but higher solidification ability and in-cabinet temperature were obtained with all Al2O3fractions compared to pure RT55.