Manufacturing processes impact many factors on a product. Depending on the selected method, development time, part performance and cost are affected. In the automotive sector, there is a growing demand for weight reduction due to the advent of electrification and the greenhouse gas emission regulations. In addition, geometric complexity is a challenging factor for the feasibility of mass production of parts. In this scenario, plastic materials are a very interesting option for application in various vehicle parts, since these materials can be molded by injection, vacuum forming, among others, while maintaining good mechanical properties. Almost a third of a vehicle’s parts are polymeric, making the development of these materials strategic for car manufacturers. This article investigates the impact of the presence of fiberglass in a thermoplastic automotive body part. Three rounds of injection simulations were performed using Autodesk Moldflow Adviser considering polypropylene with 20 %, 30 %, and 40 % of fiberglass in its composition. A parametric analysis is performed and the performance curves for volumetric shrinkage at ejection and deflection are plotted. The higher the fiberglass percentage, the higher the impact strength, dimensional stability, and stiffness.