Radar sensors are today found in a wide variety of vehicles. The radar principles used in motor vehicles today have characteristics that differ from other application domains. Thus, in addition to the physical fundamentals of radar technology, the technological aspects of automotive radar sensors are described. This results in an understanding of the potential and limitations of this very powerful technology. Several examples explain radar sensors currently on the market, which, driven by increased requirements of driver assistance systems and automated driving, reveal the development trends of recent years towards higher performance.