Heavy-duty vehicles contribute a significant and increasing portion of global greenhouse gas emissions. The objective of this study is to provide an overview of heavy-duty vehicle efficiency policies in major markets to better inform the global evolution of climate mitigation measures. The paper compiles information from those four nations that have adopted some form of heavy-duty vehicle fuel economy standards—China Japan, United States of America (USA), and Canada—plus the European Union. Despite widespread differences, the study finds that each jurisdiction used simulation modeling to some extent to minimize the cost of chassis-based compliance testing. Further, the study identified several common elements under development for the next round of policies, including (1) how to incorporate trailer manufacturers into existing regulatory structures, (2) how to add new test procedures to fully account for potential benefits from hybrids and advanced transmissions, and (3) how to address the tension between separate test procedures for fuel economy and conventional pollutants. The paper concludes with a discussion of opportunities and challenges for aligning national policies in the future.