we improve still further the crashworthiness of a tubular - frame chassis by providing a means for absorbing lower - energy impacts without deforming the tubular steel frame , the vehicle comprises a chassis structure including a load - bearing tubular chassis member extending longitudinally within the vehicle , at least one crush structure located laterally outside of the chassis member , the crush structure having an upper and a lower extent that overlap with an upper and lower extent of the chassis member . in this way , the crush structure is able to interact with the chassis member , transferring impact forces to the chassis member and thereby reducing the necessary size of the crush structure . the crush structure is preferably removable , to allow replacement after an impact . alternatively , the crush structure part of a door of the vehicle , positioned as necessary when the door is closed .