This research investigates the effects of a rear-mounted flat wing on a sports car. The work is computational, the model is two-dimensional, and the driving speed is constant. The flat wing has rounded leading and trailing edges and is angled downward with a negative angle of attack. The study found that installing a flat wing on the car's trunk generates a downward force, which is beneficial in preventing loss of tire traction, especially at high speeds. However, the plate also increases the drag force, increasing fuel consumption. Additionally, the study revealed that the flow field around the vehicle is complex, with the wing creating an additional wake region that increases drag. The expanded wake region behind the car is larger when the wing is present, explaining why the drag force increases for the winged vehicle. The study concludes that the benefits of installing a flat wing on a car's trunk vary depending on the application. For instance, vehicles moving fast, such as race cars, may benefit from the wing because it generates a downforce even though it increases drag. On the other hand, a vehicle that needs a high top speed also needs road tire traction, which comes with the wing's downforce. Nonetheless, the downside of heightened drag is that it results in more fuel usage.