The objective of our study was to investigate the properties of the BioRID II and RID2 dummies regarding repeatability and reproducibility as well as their suitability to identify the protection potential of different car seats. For repeatability and reproducibility tests, three BioRID II and three RID 2 dummies at current build levels were seated on a rigid bench seat equipped with a head restraint, and mounted on a HyGe-type sled. The test velocity was prescribed by the proposed ISO-Pulse. For testing the interaction of the dummies with varying car seat geometries and mechanical properties and their ability to assess the protection potential of the seats, three seat types with passive and one seat with an active head restraint system from different car manufacturers were used. The seats were chosen due to their injury protection potential, indicated by accident field data and results of seat evaluation tests. One BioRID II equipped with a T1-load cell and one RID2 were positioned side-by-side on identical seats for each test. The tests were performed at velocities prescribed by the ISO-Pulse (Δv 16km/h / 8 g max.) and a more severe pulse (Δv 24km/h / 13 g max.). The dummy responses were interpreted by applying all currently proposed whiplash injury criteria (e.g. NIC, Nkm, NDC, LNL). A comparison of these criteria shows their sensitivity for identification of the respective seat protection potential. This study examines the repeatability, reproducibility, kinematics and sensitivity of these two dummies in sled tests as well as their suitability with regard to the different injury criteria. The RID2 exhibited better repeatability and reproducibility than the BioRID II, because of its simpler mechanical design. The dummies did not give a consistent ranking of the low-speed, rear-end impact protection potentials of the four seat evaluated. More experience is needed to decide which dummy, injury criteria and limits should be used to assess the whiplash protection potential of seat designs.