Modularity in product architecture and its significance in product development have become an important product design topics in the last few decades. Several Product Modularity definitions and methodologies were developed by many researchers; however, most of the definitions and concepts have proliferated to the extent that it is difficult to apply one universal definition for modular product architecture and in product development.Automotive seat modular strategy and key factors for consideration towards modular seat design and assemblies are the main focus of this work. The primary objectives are focused on the most “natural segmentation” of the seat elements (i.e., cushions, backs, trims, plastics, head restraints, etc.) to enable the greatest ease of final assembly and greatest flexibility for scalable feature offerings around common assembly “hard-points.” Additionally, modular design disciplines enable a “lean” strategic approach that standardizes assembly, parts, and Bill of Process for the greatest efficiencies. A comparison of integrated seat system design and assembly with modular strategy and assembly reveals that a carefully designed modular seat system is not only cost and time-effective, from an assembly and product development point of view but it also crucial for serviceability and early failure mode detection and avoidance. The Design Structure Matrix (DSM) methodology was used to represent the seat system parts and relations between them and identify its logical modules.It is clear that modular seat system design is essential for managing variety. It improves engineering efficiency by balancing of functional/attributes requirements, product design, manufacturing, assembly, and supply-chain management.