From low to high-speed, vehicle accident is high risk of the world according to the world health organization WHO. In this thesis, two different approaches were applied to investigate crashworthiness of the crash box and bumper beam models. Localized heat treatment were applied for the crash box and a bioinspired structure were mimicked for the bumper-beam crash using false banana. An explicit dynamic impact experimental model were used in the numerical analysis. All the numerical analysis for the crash box and the bumper beam were done by adopting New Car Assessment Program (NCAP) standard. The material that were used for both crash box and bumper beam models were ASTM A992 steel. For the crash box, the crashworthiness of 26 alternative models were compared with an existing Peugeot 3008 crash box model. Again, the effect of pitch variation and sequence of the soft and hard region on the crashworthiness were analyzed. For the bumper beam, 11 alternative crashworthiness structural models were compared in different levels with the existing Peugeot 3008 bumper beam model. The level of investigation for the bumper beam includes two-stage of false banana (coba) structural adaptations. The first one is on cross-section and the second is in the adaptation of reinforcement. Both adaptations were inspired from the false banana stem. After the numerical analysis, using complex proportional assessment method (COPRAS) the best performing model were selected. From the result of this study, among 27 alternative crash box models, the crash box model with equal soft and hard region 10 mm dimensioning along the height (CB_22) scores 100-priority risk with maximum significance. Among 11 bumper beam alternatives, the Bahir Dar 4th model with a reinforcement at 900 (BD_04_900) shows a 25 % advantage from its 2nd best compotator Peugeot 3008 model in significance and priority measures. For the new bumper subsystem, a full sized and 40% offset crash scenario test setups were analyzed numerically and compared with the existing Peugeot 3008 bumper subsystem model. For the full-sized crash scenario, the new bumper subsystem model outperforms the Peugeot 3008 model. For the 40% offset crash scenario, Peugeot 3008 model outperforms the new bumper subsystem model. In general, the adopted techniques show a tremendous effect on the crashworthiness of crash box and bumper beam. This creates a new outlook in the advancement of passive vehicle safety design.