Spatial sensor systems in cars are gaining more and more importance. Such sensor systems are the foundation of future safety systems, such as automatic emergency brakes, as well as for interactive driver assistance systems. We have developed a system that can visualize such spatial sensor data. Two environments are supported: A laboratory setup for off-line experience and a car setup that enables live experience of spatially aligned laser scanner and video data in real traffic. We have used two visualization devices, a video see-through LCD Flat Panel (TFT) and an optical see-through Head-Mounted Display (HMD) in both setups. For the laboratory setup, a back-projection table has been integrated as well. To present data in correct spatial alignment, we have installed tracking systems in both environments. Visualization schemes for spatial sensor data and for geometric models that outline recognized objects have been developed. We report on our system and discuss experiences from the d...