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Heavy-Duty Diesel Vehicles

Heavy-duty diesel vehicles include long-haul trucks, buses, and other vehicles that are heavier than 26,000 lbs gross vehicle weight rating. Diesel vehicles are heavy hitters in the fuel consumption arena.

Biodiesel, which is mainly used as a blend, can be used in most heavy-duty diesel vehicles with no engine modification. The most common biodiesel blend is B20, which is 20% biodiesel, 80% conventional diesel. B5 (5% biodiesel, 95% diesel) is also commonly used in fleets. To learn more about this fuel, go to the Biodiesel section or the Alternative Fueling Station Locator.

Emissions

Currently most heavy-duty diesel vehicles are equipped with both oxidation catalysts that reduce carbon monoxide (CO), and hydrocarbon (HC) emissions, and particulate matter (PM) traps that reduce PM emissions as well as CO, and HC emissions. In combination these devices can decrease CO by 80%, HC by 90% and PM by 98%.

Oxides of nitrogen (NOx) emission are mostly controlled through advanced combustion strategies, such as, exhaust gas recirculation (EGR). In order to meet future emission standards emission control devices, such as, lean NOx traps (LNT) or selective catalytic reduction (SCR), which uses ammonia in the form of urea as a reductant, may be needed on some vehicles to meet these emission standards. These devices can reduce NOx by 70-80%.

Clean Diesel

Ultra-low sulfur diesel (ULSD)—which is called "clean diesel" when used in conjunction with advanced emission control devices—is available at fueling stations nationwide and can be used in any diesel vehicle. This fuel reduces the sulfur content in diesel fuel by 97%. Europe has used ULSD for several years. The United States began its changeover to ULSD in June 2006, after the U.S. Environmental Protection Agency (EPA) mandated that 80% of highway diesel fuel produced or imported contain 15 ppm or less sulfur. For more information, see the Clean Diesel Fuel Alliance.

In keeping with EPA's mandate, the U.S. Department of Energy's (DOE) Vehicle Technologies Program focuses on increasing heavy-duty diesel engine efficiency significantly above current levels, as well as addressing efficiency penalties resulting from technologies employed to meet increasingly stringent emissions standards. Research in this area supports the goal stated by the 21st Century Truck Partnership to develop and validate a commercially viable, 50%-efficient, emissions-compliant engine system for Class 7 and 8 highway trucks by 2010. For more information on diesel engines, read DOE's Diesel Engines Just the Basics fact sheet (PDF 267 KB). Download Adobe Reader.

Idle Reduction

Studies have shown that a typical long-haul tractor-trailer idles approximately 1,830 hours per year. Across the industry, this practice consumes more than 800 million gallons of diesel fuel annually. It also contributes to air pollution and noise. Learn more about Idle Reduction strategies for long-haul trucks and view Truck Stop Electrification Sites across the country.

Fuel Economy Improvements

Go to the Fuel Economy section to learn how strategies such as low-rolling-resistance tires and aerodynamic options help improve heavy-duty vehicle fuel economy.