New regulations such as CAFE are pushing OEMs to look for options to increase vehicle mileage. Increasing combustion efficiency, alternate fuels and weight reductions are front runners in this quest. Due to limited scope of improvement in first two options, weight reduction is considered as more feasible option. Composite materials have long been used in Aerospace-aviation industries for weight reduction. So, usage of composite materials is gaining popularity in automotive industry also. Composite manufacturing is still an expensive and time consuming procedure, so virtual prototyping is being used to evaluate design, very early in the product cycle, to reduce physical prototype testing. In this paper we have tried to demonstrate how designers can easily analyze automotive components using virtual prototyping. Starting from CAD, general workflow of composite structure modeling to optimization is discussed. Structural simulation results for composite Door are presented and are also compared with the same component made up of traditional materials.