Reformulated diesel fuels can effectively reduce oxides of nitrogen and particulate emissions from all diesel vehicles. These fuels have reduced sulfur, reduced aromatics, and increased Cetane Number. However, certain technologies are especially sensitive to the sulfur content of the fuel. Therefore if very stringent control of NOx and PM is needed, sulfur levels will need to be reduced to 50 ppm or less.

With regard to gasoline fueled vehicles, the use of catalyst exhaust gas treatment requires the elimination of lead from gasoline. This change, which has occurred throughout most of the world, has resulted in a dramatic reduction of ambient lead levels. Other gasoline properties that can be adjusted to reduce emissions include, roughly in order of effectiveness, sulfur level, vapor pressure, distillation characteristics, light olefin content, and aromatic content (Sawyer, 1993).

It is worth noting that the Japanese oil industry accelerated the introduction of near zero sulfur levels in both gasoline and diesel at a faster rate than the government required not only to facilitate the introduction of advanced NOx and PM controls on vehicles but also to increase the opportunities for more fuel efficient technologies and lower CO2 emitting technologies to enter the marketplace (E-mail from Ms. Mikami of JPEC to Ms. Aables, CAI Secretariat, 2006).