The dispersion of hydrogen leaking from a fuel tank of a hydrogen-powered sedan into its interior is simulated in this paper. The effects of two different ventilation systems on the evacuation of the hydrogen are compared. Results are presented as illustrations of the steady state hydrogen concentration distribution in the sedan. The study demonstrates that a modified ventilation system can greatly reduce the risk of hydrogen combustion or explosion in the sedan interior. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.