The objective of this study is to generate new knowledge and insight on the subject of shipping‘s technical and operational energy efficiency, both to assist shipping industry stakeholders in understanding the statistics and drivers of energy efficiency in the markets in which they are operating, and to contribute to the ongoing discussions in the policy sphere around energy efficiency and GHG emission reduction. This study, which is the first to use Satellite Automatic Identification System data to analyse the energy efficiency of the global fleet, is also intended to act as an evaluation of this new data source and a discussion of its benefits and any shortcomings when used for the estimation of energy efficiency. Studying the fleet in 2011, this study‘s particular focus is on the extent to which the recent phenomenon of ̳slow steaming‘ has influenced operational behaviour in different fleets (ship types and sizes), and the probable consequences to energy efficiency. As well as describing the technical and operational efficiency of different fleets of ships, analysis is also undertaken to assess whether energy efficiency appears to be represented in prices (time charter, newbuild, second-hand) in different markets and in the selection of ships for scrapping.