The present study explores opportunities and challenges to increase energy efficiency in government vehicle fleets through electrification. It identifies international best practices in relation to fleet electrification, suggests the most suitable comprehensive approach for a fleet transition, and recommends the most immediate actions to deploy. Considering the leading role that the public sector plays in promoting the use of renewable energies and enhancing energy efficiency, the study presents a roadmap for government fleet transitions of vehicles that have equivalent alternatives in the market.Executive summary .-- Introduction .-- I. Fleet transition phases .-- II. Readiness phase .-- III. Implementation .-- IV. Follow-up .-- V. Funding alternatives .-- VI. Final considerations.