This paper describes the effect of fuel sulfur levels on vehicle emissions. The project was undertaken to provide a basis for lowering sulfur levels in fuel in order to establish necessary vehicle emission standards. A matrix was developed to describe the relationship between fuel sulfur levels and vehicle emissions based on vehicle testing data in China and the literature research. The matrix was then integrated into a vehicle behavior forecasting spreadsheet to analyze the vehicle emission reduction potentials under several fuel desulfurization scenarios. The results of comparing the total emissions in typical years for several scenarios show that the best emission control effect can be achieved by completely matching the fuel sulfur requirements with the emission standards. This assessment of vehicle emission standards and refinery costs to produce low sulfur fuel provides a critical insight into the importance of reducing fuel sulfur as emission requirements become more stringent. (C) 2008 Elsevier Ltd. All rights reserved.