Four commercially available neck collars were evaluated in forward facing (-G_x) impacts using an instrumented Hybrid III dummy. Each was tested twice at 14ms^-1 and -25G_X. A full-face helmet was worn and four control impacts were conducted without a collar. Head accelerations and HIC, and shear forces and moments about the upper and lower neck were recorded, and the impacts were monitored by high speed video (200 fps). Only one collar had any demonstrable effect, reducing the moment about the lateral head axis, M_y. It is concluded that proper specifications are needed to ensure the efficacy of neck collars for racing car drivers.