The use of hybrid nanofluids is seen as a rarely studied approach in terms of thermal efficiency and still worth investigating. In this article, the effects of ZnO + Pure Water nanofluid and hybrid nanofluid ZnO + CuO + Pure Water nanofluid, used as coolant fluid in a commercial automobile radiator, on radiator cooling performance were experimentally investigated. In addition to this investigation, the effects of using several types of vehicle front grilles on cooling performance were also experimentally examined. In the study, pure water tests used for validation were first conducted, and the prepared nanofluids were tested respectively. The fluid inlet temperature to the radiator was 70 degrees C, the air inlet speed was 6 m<middle dot>s-1 to 8 m<middle dot>s-1 to 10 m<middle dot>s-1, and the fluid flow rate was 17 L<middle dot>min-1 to 19 L<middle dot>min-1 to 21 L<middle dot>min-1. The fluid concentrations used in the tests were as follows: 100 % pure water, pure water-based nanofluid containing ZnO particles at 0.3 % concentration, and hybrid nanofluid containing 0.15 % ZnO and 0.15 % CuO nanoparticles. At the end of the tests, the cooling performance was calculated by measuring the flow rate, pressure, speed, and temperatures of different coolant fluids and air, with the highest cooling performance achieved in the hybrid nanofluid with a 52 % increase. In addition to using this nanofluid, the effects of using front grilles with decreasing, increasing, and constant cross-sections toward the center on cooling performance were also examined, and the cooling performance was increased by up to 66.5 % by finding the optimum front grille geometry.