This investigation studied numerically the aerodynamical effects of different modifications in a model of a common sedan. Four car modifications as spoiler, wing profile spoiler, standard diffuser and curved diffuser and their combinations were reported. Using a threedimensional sedan model created with Computer-Aided Design software, the modifications are applied and assessed their influence on aerodynamics at speeds ranging from 60 to 120 km/h. AThe spoiler, wing spoiler, standard diffuser and curved diffuser reducing the lift forces experienced by the vehicle. Three cases, spoiler, wing spoiler, and curved diffuser increase the drag forces Combining a curved diffuser and a spoiler significantly decreases lift forces by an average of 77.8%, Aalbeit with a 15.3% increase in drag forces, by 120 km/h The synergy of a curved diffuser and aAwing spoiler achieves a substantial 63.3% reduction of net vertical forces, with only a 7.9% increase in drag forces, by 120 km/h, offering improved control with lesser energy consumption in comparison to other combinations. Results show that modifications, greatly influence airflow interaction, with effects varying by speed. Importantly, the impact of using two modifications is not a simple sum of their individual effects; and it must be assessed thoughtfully alongside airflow alterations.