||The hydrogen filler mouth provides firm contact with the filler nozzle, is equipped with a highly reliable filter, and employs a check valve of unitized construction for an excellent hydrogen seal. This design prevents the mixing in of other gases or the connection of filler nozzles with the wrong fill pressure. Further, a grounding system rids the vehicle of static electricity before fueling. The safety design positions the hydrogen filler mouth opener inside the grounding lid, requiring that the grounding lid be opened before the opener can be operated. There is also a system that prevents driving during fueling to further ensure safety.