The objective of this paper is to develop a linear programming (LP)-based approach in order to compute the CO2 emissions associated with the marginal production of gasoline and diesel oil within a refinery. The LP model developed by the Institut Francais du Petrole is then applied to a typical French oil refinery that has to meet new ultra-low sulfur specifications for these automotive fuels. The main conclusions of this study are that (1) further marginal production of diesel oil would be more CO2 intensive and, (2) the gap between the marginal CO2 coefficients of gasoline and diesel oil would be widened because of the more energy-intensive adjustment of diesel oil properties to the new European standard requirements. Furthermore, the LP-based methodology presented in this paper can provide useful information for prospective Well-to-Tank analysis to guide policy makers. In particular, the marginal CO2 coefficients obtained from the optimal solution can be used as input data in such an analysis to have a representative view of the environmental effects of gasoline and diesel oil production within the refinery. (C) 2008 Elsevier Ltd. All rights reserved.