Here are some of the primary differences between clean diesel fuel — which is the standard in North America today — and previous formulations. Diesel • Contains higher amounts of sulfur. • Creates higher soot emissions. • Higher overall cost when compared with clean diesel. • Ignites through compression rather than with spark plugs as in gasoline engines. • Has the highest energy density rating among transportation fuels, meaning vehicles get more energy per gallon from diesel than gasoline or other fuels. • Has been in use for more than 120 years. Clean Diesel • Contains 97 percent less sulfur than traditional diesel blends. • Reduces emissions by 10 percent when no other measures are taken. • When used in advanced engines with emissions control measures, clean diesel reduces emissions up to 95 percent over traditional diesel. • Offers lower costs to drivers when used in conjunction with high-efficiency engines and emissions-control systems. • Biodiesel also can be considered clean diesel because of its low sulfur content. • Is now the standard for diesel engines nationwide.