Stringent emission norms by government and higher fuel economy targets have urged automotive companies to look beyond conventional methods of optimization to achieve optimal design with minimum mass, which also meets the desired level of performance targets at systems as well as at vehicle level. In conventional optimization method, experts from each domain work independently to improve the performance based on their own domain knowledge which may not lead to optimum design considering the performance parameters of all domains. It is time consuming and tedious as it is an iterative method. Also it fails to highlight the conflicting design solutions. With increase in computational power automotive companies are now adopting Multi-Disciplinary Optimization (MDO) approach which is capable to handle heterogeneous domains in parallel. It facilitates to understand the limitations of performances of all domains to achieve good balance between them. The paper presents the MDO of a Tail door of an SUV which is carried out at the stage where major structural design has been finalized and only gauges of the tail door panels can be taken for design variables. Objective of the exercise was to minimize mass while meeting various performance parameters. Modal and FRF load cases are considered for NVH domain and stiffness load cases for durability domain. Crashworthiness domain load cases were not considered here since they did not affect the tail door design. Response surface based optimization method has been selected for the optimization considering resource availability and dexterity of being applied in various domains. Sensitivity study was used to identify critical panels for each performance parameter. Broken constraint charts were studied to identify the load cases which limits the mass reduction opportunity. The study showed nine percent of mass saving which is significant for automotive closures.