One-dimensional, lumped-mass models for predicting the dynamic response of vehicles in crashes have been used extensively in recent years. The energy-absorbing characteristics, i.e., the load/deflection data, for use in the models are determined from static crusher tests of actual vehicle components. In order to account for the crush rate effects on the structure, a transformation is needed to extrapolate the statically obtained data to the dynamic case. The transformation factors - the static-to-dynamic amplification factors - are empirically derived and have been reported by some investigators to be linearly and by others to be logarithmically related to crush rate. This paper reports on the development of dynamic amplification factors for vehicles with framed structures, e.g., light trucks and S-framed cars, and unibody cars. The factors were developed by exercising lumped-mass models with various forms of dynamic amplification factors and comparing the model results with results from crash tests. The factors that best explained the crash tests are different for different construction vehicles.