The validation of ADAS/ADS poses a significant new challenge to the automotive industry due to a proliferation of new standards, legal and consumer requirements. All stakeholders behind these requirements realise that there is a need to cover an infinite space of possible instances of thousands of scenarios. Furthermore ADAS/ADS validation for a specific vehicle will not end with the sale of the vehicle. Continuous improvement and over-the-update will make it necessary to execute the validation cycle multiple times during the lifetime of a vehicle. Having said all this it is clear that only by means of virtual simulation it will be possible to handle the huge amount of required tests. However if only a fraction of a percent is being tested experimentally to validate virtual tests, the number of real tests will explode. These real tests are needed to complement the virtual testing and will address four major categories: - Testing for validation of virtual simulation - Testing for safety-critical and edge cases - Testing to ensure robustness of the ADAS/ADS - Testing for generating trust („No trust, no use“) In-door testing promises to be significant contribution to the handling of the large number of physical tests by providing a reproducible, efficient, safe and secure environment which proving ground or road testing cannot deliver. The advantages include fully controllable environments, high through-put, fully adjustable test parameters for robustness studies and enhanced safety through reduction of total test energy. The presentation will elaborate on these advantages and also discuss some of the challenges that are new to in-door testing, like the lack of GNSS coverage.