Advanced driver assistance features like Advanced Emergency Brake Assist, Adaptive Cruise Control, Blind Spot Monitoring, Stop and Go, Pedestrian Detection, Obstacle Detection and Collision Detection are becoming mandatory in many countries. This is because of the promising results received in reducing 75% of fatalities related to road accidents. All these features use RADAR in detecting the range, speed and even direction of multiple targets using complex signal processing algorithm. Testing such ECUs is becoming too difficult considering the fact that the RADAR is integrated in the PCB of ECU. Hence the simulation of RADAR sensor for emulation of various real world scenarios is not a preferred solution for OEMs. Furthermore, Tier ones are not interested in a testing solution where the real RADAR sensor is bypassed. This paper discusses such issues which include the validation of the most modern Electronic Scanning RADARs. These instruments could detect even up to 64 dynamic targets in multiple directions using a single RADAR module. HILS based test solutions without bypassing the RADAR sensor for the real time validation of RADAR related features is discussed in detail in this paper. Paper also explains about the RADAR target simulators and its synchronization with real world behavior.