This thesis comprises a programme of work investigating the use of active human computer models and the effects of forthcoming automotive safety features on vehicle occupants; more specifically, their unbelted kinematics and sustained injuries. Since Hybrid III anthropometric crash test dummies are unable to replicate human occupant kinematics under severe braking, the thesis highlighted the need to research the most appropriate occupant computer model to simulate active safety scenarios. The first stage of the work focussed on occupant kinematics and developed unique human occupant reflex response target curves describing the head and torso relative angle change as a function of time, based on human volunteers’ low deceleration sled tests. These biomechanics curves were, subsequently, used to validate an active human model, asserting its torso response, while confirming that further development in its neck response was necessary. The sled test computer validation proved that only an active human model was suitable to model a pre-braking phase. The second stage of the work combined the occupant’s kinematics of the pre-braking phase, followed by a subsequent frontal crash into a rigid barrier inducing an airbag deployment. The results suggested that, in a 1g frontal deceleration pre-braking phase, the kinematics of an unbelted occupant within the vehicle compartment was complex and in some cases extreme. With the parameters adopted within this unique study, it was observed that occupant motion and position relative to the airbag system varied depending on awareness level, seat friction, braking duration and posture. Additionally, it was observed that a driver holding the steering wheel with one hand could be out of the airbag deployment reach due to extreme Out-Of-Position (OOP). Results also concluded that the dynamic OOP scenario was intricate and would yield to higher occupant injuries. Future studies, into brake dive, seat geometry, seat stiffness and cabin packaging, are recommended to capture the vehicle configuration providing the highest dynamic OOP safety risk. Finally, the investigations conducted, as part of this doctoral programme, led to the provision of new knowledge in the validation of active human models, a unique demonstration of the importance using human computer models, rather than crash test dummies, as well as the potential for the evaluation of future restraint systems in dynamics unbelted OOP, considering various posture scenarios.