The increasing number of road traffic accidents (RTAs) worldwide has underscored the need to better understand the mechanisms of trauma, particularly in vulnerable thoracic tissues like the aorta and diaphragm. This chapter investigates the mechanical behaviour of these tissues under high strain rate loading conditions, which are typical during automotive collisions. The experimental characterization of the aorta and diaphragm provides insights into their viscoelastic properties and rate-dependent failure mechanisms, which are critical for enhancing the accuracy of human body finite element (FE) models used in crash safety simulations. Advanced constitutive models were developed using data from dynamic testing methods, including uniaxial and biaxial tensile tests, as well as Split Hopkinson Pressure Bar (SHPB) experiments. The findings reveal significant variations in tissue stiffness, elasticity, and failure thresholds at elevated strain rates, which contribute to the understanding of soft tissue injury mechanisms during high-speed impacts. This work aims to improve biofidelity in FE models of the human body, thereby offering more accurate predictions of injury risks and aiding in the development of better vehicle safety systems.