Impact energy absorption system for vehicles

An impact energy absorption system for vehicles, comprising a cross member (16) housing a series of composite alveolar structures or buffers (10, 10A) which co-operate with an element (14) made of foamed plastic resin; the alveolar structure (10, 10A) is made of plastic resin preferably derived from polycarbonate and can feature a taper at at least one of the longitudinal ends where a containment element (22) can be provided.