A novel method of simulating side impact has been developed, resulting in a representative and economical dynamic test, which can be performed various stages in vehicle development programmes. The technique utilizes a conventional HyGe sled test facility, with a set of two purpose built sleds. The first of these, the striking sled, represents a mobile barrier which can be ballasted and carry a deformable face to either the Federal or European specifications. This sled is propelled rapidly and accurately to speed by the HyGe accelerator. The second (struck) sled carries a vehicle bodyshell or representative side structure with trimmed doors, seats and dummies installed. Mounting 0f the bodyshell is important in ensuring a high degree of correlation with full vehicle crash tests. The sled complete with bodyshell and payload is ballasted to vehicle curb weight, and moves away after impact by the striking sled under simulated tyre friction. The first part of a series of tests being conducted in the development of the S.I.D.E. Procedure is described and comparison made between the results and those of full vehicle crash tests conducted on nominally identical vehicles.