ABSTRACT With reference to existing literature, most OEMs are working on reducing product development time by around ~20%, to achieve seamless integration to digital ecosystem and focusing on new features catering to dynamic customer needs. The Systems Engineering approach focuses on functions & systems rather than components. In this approach, designers (Computer Aided Design) / analysts (Computer Aided Engineering) need to understand program requirements early to enable seamless integration. This approach also reduces the number of iterative loops between cross functions thereby reducing the development cycle. In this paper, we have taken a common challenge faced by Closures (Liftgate) engineering to meet slam durability fatigue life, replicating customer normal and abusive closing behavior. For modern vehicles, with faster vehicle development process, major challenges are balancing mass with improved structural and durability performance while also considering design changes with frequent changes to styling without impacting timing and cost. The program we studied had a mass addition of ~15% due to added content in Liftgate subsystem based on styling changes. With increased mass of liftgate, an abusive liftgate slam resulted in increased impact force of ~30% leading to fatigue failure being observed on critical components. This brings a need for Agile methodology to solve fatigue problems in fast-track vehicle programs. The developed approach improves liftgate fatigue life by tuning the liftgate impact force. Liftgate impact force is related to (a) mass of the Liftgate assembly, (b) the stiffness of critical interfaces, (c) energy absorption mechanisms and (d) manufacturing variation. Design of experiments (DOE) need to be done with these critical variables and report fatigue life values. Further, design iterations should be performed until the requirements are satisfied. New developed methodology will help designers to answer several "what if" scenarios. Such as, what if mass changes by ~5%, critical interfaces stiffness change by ~5%, interface impact forces change by ~5%. The outcome of this study will help designers to upfront develop design concepts based on the design changes to critical variables. This methodology was applied on a program by changing the designs to reduce impact force and improve fatigue life. Design changes were (a) mass reduced by minimizing liftgate applique & sheet metal thickness, (b) Liftgate stiffness changed to modify load paths, (c) energy absorbing components like bumpers & liftgate seals were tuned to change compression load deflection & (d) design robustness study done considering manufacturing variations like sheet metal thinning, weld position, material variations etc. In the worst combination of variables, the impact force at closing resulted in fatigue life issues on common/supplier parts. Based on learnings, design changes were recommended on supplier components to improve fatigue life. Then, supplier performed component level accelerated test to validate the design change. This Agile methodology helped us to move from a point-based design approach to a set-based design approach, meeting Liftgate's fatigue life and mass target.