As emissions from the global road freight transport sector continue to rise, an understanding of how emissions are produced, estimated and measured is increasingly important. This paper identifies the key influences on greenhouse emissions from heavy-duty diesel trucking, and evaluates the reporting options currently available under the Australian National Greenhouse Emissions Reporting Scheme. The latter is done through a case study of emissions modelling, used to illustrate the trade-offs in different reporting options. The paper concludes that routine reporting based on method 2 should deliver more accurate reportable emissions, as well opportunities to better understand emissions profiles and strategies for reducing emissions.