A cross member passes a longitudinal member. The cross member is connected, on its outer end, to a side sill assembly and includes a connecting portion that divides the cross member into a remote cross member portion from the outer end of the cross member, and the other cross member portion. A reinforcement element extends through the connecting portion into the remote cross member portion and terminates in at its inner end spaced by a gap from a top wall of the longitudinal member, and it extends into the other cross member portion and terminates in at its outer end in the neighborhood of the side sill assembly. It is connected to an upper inner wall of the remote cross member portion, but spaced from an upper inner wall of the other cross member portion.