The Southern Alliance for Clean Energy has a Municipal Policy Toolkit for cities or counties that want to encourage a transition to clean transportation. https://www.electrifythesouth.org/toolkit
This is for all aspects of transportation, not just fleets the city or county maintains. It has major topics with specific examples and tools for subheadings within each major topic. Some of the major topics include: Create an Overarching Transportation Electrification Plan, EV Municipal Fleet, EV Charging and Infrastructure (private residences, multi-unit residences, public areas, etc.), and several more.
It is a very helpful and very practical toolkit. Anyone, anywhere, can share it with their city or county officials.
