Over the past decade, diesel hade made large advances in the French and European automobile markets. In 1995, diesel could account for half of all private vehicle registrations in France, and a quarter in Western Europe. This situation inevitably raises a number of problems: environmental problems, because the diesel engine emits more nitrogen oxides and particulates than the gasoline converter, and also because the French refining industry is no longer able to meet domestic demand. Furthermore, starting 1st October 1996, according to the new European specifications, the sulfur content of road diesel must not exceed 0.05%. This prospect of the production of highly desulfurized motor fuels will directly affect the hydrogen balance of the refinery, and hence self-consumption and CO2 emissions. This study is aimed to assess the environemental impact of the reduction of the diesel sulfur content from 0.3 to 0.05%. The review covers the entire energy cycle, from oil extraction to fuel combustion in the engine. Gains and losses in terms of local and global pollution are evaluated according to the type of hydrogen used (partial oxidation of vacuum residuesor coal, steam reforming of natural gas or electrolysis naphtha) and the type of feedstock (straight run gas oil or light cycle oil) in the hydrodesulfurization process.