In many industries, such as aerospace and biomedical, additive manufacturing (AM), which encompasses several technologies, has already proven to be disruptive. In the automotive sector, historically based on mass production, the transition to digital manufacturing can be supported by AM in some specific cases although further research is needed to verify technological feasibility as well as economic and environmental sustainability. This paper discusses the integration of a multi-jet fusion (MJF) system into actual automotive production lines for the manufacture of polymer components in a mixed resource production system. Capacity utilization and time-based key performance indicators (KPIs) are considered for the design of the production line, while single- and multi-part manufacturing strategies are compared. A cradle-to-gate life cycle assessment is carried out, focusing on cumulative energy demand and carbon dioxide emissions. The results show that, for the specific case study, the cell-layout AM-based production line has proved to be suitable for small-to-medium batch production, and the single-part strategy could be recommended to avoid potential part inhomogeneity and an additional manual sorting step. This study presents a novel framework for integrating productivity, economic, and environmental performance metrics to advance the adoption of AM in traditional manufacturing environments.