In this paper the energy absorption of thin-walled aluminium tubes used as crash boxes in the body structure of a vehicle has been optimized. In order to achieve this, various cross-sections of extruded aluminium were chosen and their behaviour under dynamic impact loading was investigated. The crash boxes were made from aluminium alloy 6060 temper T4. Finite element software LS-DYNA in ANSYS was used for modelling. For each cross-section, the results of dynamic crushing load versus crushing distance was obtained from the FE simulation and the results were compared with the experimental and numerical work on a square crash box in the literature. Parameters such as the crush force efficiency and the specific energy of various crash boxes were compared with the relevant ones for the square crash box and the most efficient crash box was recommended.