A 3D CFD underhood thermal simulations are performed in two different vehicle platooning configurations; (i) single-lane and (ii) two-lane traffic conditions. The vehicle platooning consists of two identical vehicles, i.e. leading and trailing vehicle. In this work, heat exchangers are modeled by two different heat rejection rate models. In the first model, a constant heat rejection rates are considered as similar to no-traffic vehicle condition. In the other model, a varied heat rejection rates are implemented by considering an aerodynamic influence on fuel consumption rates. In a constant heat rejection rate model, the trailing vehicle thermal performance is significantly dropped in single-lane traffic due to reduced oncoming cold mass air flow velocities from leading vehicle. Also, the similar observations are found in two-lane traffic but at higher vehicle separation distances. In a varied heat rejection rate model, significant drop in temperature raise is observed in both leading and trailing vehicles when compared to a constant heat rejection rate model in the single-lane and the two-lane traffic conditions. In leading and trailing vehicles, the varied heat rejection rates are obtained from fuel consumption rates.