This paper presents a comprehensive and validated inventory of road transport emissions worldwide. The bottom-up calculation correlates within 2% and 10% with fuel sales data in Organisation for Economic Co-operation and Development (OECD) and non-OECD regions, respectively; this adds credibility to the results. The inventory covers eight exhaust compounds emitted by five vehicle categories and five fuel types each. For many non-OECD countries, road transport exhaust emissions have been calculated for the first time at this level of detail. Furthermore, this paper provides a conservative estimate of primary particulate matter emissions from diesel and gasoline vehicles. The Group of Seven countries (Canada, France, Germany, Italy, Japan, the United Kingdom, and the United States) together with Brazil, China, India, Mexico, and Russia account for more than three-quarters of all considered exhaust emissions, followed by major countries in the Middle East and Southeast Asia. Action in these 15 countries could reduce emissions for the whole region significantly. Exhaust control and maintenance can focus on motorized two-wheelers, buses, and heavy-duty trucks. The inventory is particularly suited for comparisons across countries and regions. Data uncertainties in transport volumes and real-world emissions, notably of hydrocarbon and particulate matter, should be reduced.