SUMMARY: NHTSA is issuing this final rule to amend Federal Motor Vehicle Safety Standard (FMVSS) No. 305@ ????Electric-powered vehicles: Electrolyte spillage and electrical shock protection@???? to adopt various electrical safety requirements found in Global Technical Regulation (GTR) No. 13@ ????Hydrogen and fuel cell vehicles@???? and other sources. This final rule updates FMVSS No. 305 using modern and harmonized safety requirements and facilitates the introduction of new technologies@ including hydrogen fuel cell vehicles (HFCVs) and 48-volt mild hybrid technologies. This final rule is a deregulatory action. It imposes no costs and adjusts FMVSS No. 305 to give more flexibility to manufacturers not only to use modern electrical safety designs to produce electric vehicles@ but also to introduce new technologies to the U.S. market. To expand FMVSS No. 305??s performance requirements beyond post-crash conditions@ NHTSA adopts electrical safety requirements to protect against direct and indirect contact of high voltage sources during everyday operation of electric-powered vehicles. Also@ NHTSA adopts an optional method of meeting post-crash electrical safety requirements@ consistent with that in GTR No. 13@ involving use of physical barriers to prevent direct or indirect contact (by occupants@ emergency services personnel and others) with high voltage sources.