This paper discusses Virtual Iteration Method (VIM) using Virtual Test Lab (VTL) to reproduce physical test to the proving ground. In general, VTL using Finite Element Model (FEM) and Multi Body Dynamics (MBD) Model is capable to describe nearly all physical behaviors of complex vehicles. However, MBD models often contain uncertain parameters such as a stiffness and damping of bushings that reduce accuracy. With the help of VIM it is possible to compensate for these imperfections and to improve the output quality for fatigue life prediction. A number of car makers are adopting CAE to obtain initial design guide line. It is still difficult to estimate durability performance using a fatigue analysis in initial stage of a vehicle development. This study proposes methods to evaluate durability in an early design stage. That is the suggestion of strength criterion to satisfy target life using the damages calculated from the load history only before the initial decision of design shapes. Through a series of these processes, load conditions and allowable stress to be able to estimate the durability performances are calculated using static strength analysis in the initial design.