Due to requirements and continuous design improvement in automobile industries, it has become mandatory to keep passenger car and seating in automobile to safest at the time of a crash collisions. Although the rear-end collision stand third among all the different four collision types, the injuries on passenger after such collision are about one-third of all collisions. This indicates that improvement of passenger compartment crashworthiness features in rear collision is a mandatory goal for automobiles companies. In recent years, computer-aided engineering tool have become great success as the usage of such tools will not only significantly reduce the cost of performing real crash test, but also saves a lot of time. This thesis is mainly concentrated on the evaluation of structural damage to a small compact car in different possible rear end collision scenarios, then evaluation of responses and potential injuries of occupant with head restraint versus without head restraint. To achieve this, simulations are performed in the LS-DYNA with finite element (FE) models, rigid barrier as well as deformable barrier according to the Federal Motor Vehicle Safety Standards (FMVSS) 301R Fuel System Integrity regulations. Based on the acceleration obtained at the driver seat of target small vehicle, cabin environment which resembles driver seat is designed in MADYMO with five rigid bodies and with a FE model of the safety belt. A Hybrid III 50th percentile dummy model is placed in the seat, and the occupant responses are examined with input acceleration obtained from the earlier FE model rear end collision simulations. In addition to this rear collision configuration, rear offset collision, rear oblique collision and oblique offset collision are also modelled in software and examined. The results obtained from this study illustrate the difference in the structural damage and injury potential to the car occupant in rear-end collision between the new and old FMVSS 301 regulations, as well as different rear end collision scenarios.