The leakage areas of the engine compartment are located essentially at the junctions between the hood and the front end, the sides, the lights, and the windshield. The present study concerns the impact of these leakage zones on the engine compartment temperatures. The study synthesizes thermal measurements carried out on a real vehicle in the wind tunnel S4 of Saint-Cyr l’Ecole France. The engine compartment is instrumented with 80 surface and air thermocouples. Measurements are carried out for three different thermal functioning points with the front wheels of the vehicle positioned on a dynamometer and driven by the engine of the car. Five configurations of leakages closing are tested.