The heat transfer performance of a hybrid nanofluid (Al₂O₃-Cu particles in water) as a coolant for automobile radiators will be investigated in this study. The primary objective is to examine its potential to improve cooling efficiency. Through experimental tests using a custom setup, the study analyzes heat transfer coefficient, thermal conductivity, and convective heat transfer to gain valuable insights into the nanofluid's thermal behavior. Positive findings could lead to an innovative and efficient cooling solution for car radiators, driving advancements in automotive engineering and sustainability. Ball milling approach was used to synthesize nanoparticles and then hybrid nanofluids at varied volumetric concentrations (0.02%, 0.04%, and 0.06%), and their heat transfer performance characteristics were then experimentally examined in an automobile radiator. A fan that creates a cross-air flow within the tube bank at a steady pace was used to facilitate forced convection heat transfer as the test liquid passed through the radiator's 37 vertical tubes. The experiment was conducted using a range of flow rates, from 6 to 14 liters per minute, and a constant 60°C radiator inlet temperature. The findings suggest that, in comparison to the pure base fluid, heat transmission was improved at all hybrid nanofluid concentrations. The convective heat transfer coefficient has increased by 24.6%, 43.16%, and 66.75% when a Cu-Al₂O₃/Water hybrid nanofluid at volume concentrations of 0.02%, 0.04%, and 0.06% was used.