CFD simulations are effectively used to cut down the vehicle development period and to completely understand the interaction between the underhood and external airflow. While the methodologies are well established to quantify the external aerodynamic behavior of vehicle, the investigations to quantify the underhood airflow behavior still requires in depth understanding, even though a vast number of studies available on vehicle underhood flow. The heat exchangers present in the underhood zone has a major impact on aerothermal management of vehicle. In general two factors affecting the performance of heat exchangers are (i) mass flow rate passing through the heat exchanger (ii) air flow distribution over the heat exchanger inlet surface. The air massflow rate and its distribution depends on the cooling airflow path in the upstream direction of heat exchanger specifically the front end design of vehicle. Most of the CFD studies in automotive industries are used to focus on predicting the cooling air mass flow rate through heat exchanger. In this study, a methodology is proposed to quantify the airflow distribution over the heat exchanger(radiator) as a function of flow statistics of the upstream cooling air. Further, this work is extended to study the impact of airflow non-uniformity on the thermal performance of radiator using the empirical equation available in literature. This study a reveals a vehicle level system trade-off between grille opening, cooling air mass flow rate and non-uniformity at design stage itself. The interpretations of this work can serve as a design guideline for the thermal system and styling engineers of automotive domain.