Several investigators have noted limitations of the most commonly used dummy in rear impact testing, the Hybrid III. A dummy for rear impact testing, the BioRID I, has previously been presented. It was a step towards an effective tool for seat performance testing, but it was concluded that its neck extension and T1 upward motion were too small and that its user- friendliness could be improved.A new BioRID prototype has been developed. It has new neck muscle substitutes with damping and elastic elements that are independent of each other and fitted inside the torso. The new neck muscle substitutes extend to T3 and thus also load the upper thoracic spine. The new dummy has a softer thoracic spine and a torso made of softer rubber than was used for the original dummy.The BioRID prototype''s performance was compared to that of volunteers, the BioRID I and Hybrid III in rear impacts at ΔV=7 km/h. The kinematics response of the new BioRID prototype appears to be more human-like than that of the BioRID I and Hybrid III. The dummy also provides repeatable test results and is more user-friendly than the BioRID I.