Creates the Government Zero Emission Vehicle Act. Provides that all vehicles owned by a governmental unit (defined as the State or a State agency) must either be a manufactured zero-emission vehicle or converted into a zero-emission vehicle no later than January 1, 2045. Requires the Environmental Protection Agency to adopt rules to implement the Act. Provides that the rules may include requirements for all governmental units to gradually reduce the percentage of vehicles that are not zero-emission vehicles up through January 1, 2045. Limits the concurrent exercise of home rule powers. Amends the State Mandates Act to require implementation without reimbursement.