Occupant protection during side impacts is a very important consideration in automobile design. To ensure occupant protection, physical tests as well as simulation using analytical models are extensively used in the early phases of design. Analytical models for side impact simulation can be developed directly from the crash measurement data and the physical insight of the crash event. In this paper, uncoupled lumped parameter models for the automobile structure and the test dummy are developed based on the study of distribution of crash energy. The model parameters are estimated using a Kalman filter estimator in a constrained environment. The estimation approach is verified using simulated data as well as test data. The modeling and application of the data based model is demonstrated in the actual design environment with an example. The data based model is shown to be very useful in understanding the contribution of various components in the overall crash performance, evaluating design trade-offs and developing component level performance targets.