This briefing paper looks closely at the Euro 6/VI vehicle emissions standards, which tighten the limits on air pollutant emissions established in prior European standards, and require the best available technology for vehicle emissions control. These standards are significant because, in the past, countries outside of Europe, the United States, and Japan have largely patterned their own emissions policies on European regulations. The authors argue that if these countries were to adopt the Euro 6/VI standards they could achieve up to a 99 percent reduction in the emission of pollutants such as fine particulate matter (PM2.5), reducing the risk of ischemic heart disease, lung cancer, stroke, and asthma for their citizens. The paper gives a history of the standards, which are for both light- and heavy-duty vehicles. It summarizes the core technical elements of the standards, reviews the control strategies available to achieve the pollutant limits, and examines the problems associated with real-world emissions.