Downsizing of transmission boxes and economic pressures in manufacture has gradually led to changed sealing conditions in passenger cars. Radial shaft seals are widely used in power transmission systems to prevent oil leakage from the system. Leaking transmission systems can lead to both environmental pollution and excessive warranty costs. It is essential to develop a dedicated experimental rig to simulate the transmission system operation under controlled environment, providing access for various sensors and data acquisition systems. A pre-requisite for representative rig design is to determine the in situ vehicle conditions which must be replicated in such a design. The paper reports on the evaluation of these in situ conditions, particularly the imposed vehicular vibration conditions.