Using the basic equations for modeling heat transfer through heat exchangers, an analytical approach is developed to determining the thermal performance of cross-flow air-cooled heat exchangers as a function of the flow statistics of the upstream cooling air. A two-dimensional computational code is also developed to calculate heat-exchanger performance in relation to the airflow topology upstream of the heat exchanger induced by its integration in complex environments such as the car underhood compartment. The analytical and numerical results show satisfactory agreement: the mean relative error in heat exchanger thermal performance determined by the numerical computation and the analytical approach is about 0.5%. (C) 2010 Elsevier Ltd. All rights reserved.