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Diesel moves approximately 90 percent of the nation's freight tonnage, and today nearly all highway freight trucks, locomotives and commercial marine vessels are powered by diesel engines.

Learn more about how More Clean Diesel Trucks Now On the Road Means Lower Fuel Consumption and Fewer Greenhouse Gas Emissions

 Emissions Reduction


A new generation of clean diesel technology is fueling new medium and heavy-duty commercial trucks. More than 95 percent of all heavy-duty trucks are diesel-powered as are a majority of medium-duty trucks.  Diesel power is the driving force today of goods movement by truck in our economy and diesel will play a central role in efforts to reduce fuel consumption, promote energy security and lower greenhouse gas emissions (GHG) in the years ahead. Diesel also provides a unique technology platform suitable for expanded use of hybrid powertrains and lower-carbon renewable fuels - both strategies for reducing GHG emissions in the future.

Clean Diesel Progress 

While continuously making commercial trucks more fuel efficient, diesel engine and truck manufacturers have also been making them dramatically cleaner, a significant accomplishment considering that increased fuel efficiency and lower emissions are near opposite and competing forces in diesel engine design. In fact, diesel vehicles manufactured after 2010 achieve an average five percent improvement in fuel efficiency, making them cleaner and more fuel efficient than ever before!

Over the last 10 years, emissions from heavy-duty diesel trucks, buses and other vehicles have been reduced by 99 percent for nitrogen oxides (NOx) - an ozone precursor - and 98 percent for particulate emissions. Consider that it would take 60 of these 2010 trucks to equal the same emissions from one pre-1988 truck. A 60-1 ratio!

In August 2011, U.S. Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) established a national program to reduce GHG emissions and establish new fuel efficiency standards for commercial vehicles beginning in 2014 through 2018. Because of the sheer magnitude of commercial vehicles operating in the United States, this regulation has the potential to result in significant emissions reduction and energy efficiency gains. The U.S. fleet of trucks consumes about 22 billion gallons of diesel fuel every year. Over the lifetime of the vehicles affected by the new rule, the program is expected to reduce oil consumption by more than 530 million barrels, result in more than $50 billion in net benefits, and reduce carbon dioxide emissions by 270 million metric tons.

Those Phase 1 rules are now implemented beginning model year 2014. Manufacturers are meeting these targets through continued advancements in engine and aftertreatment technologies along with advanced aerodynamics, transmission, tire and other technologies that improve fuel economy. According to NHTSA, technologies deployed to meet these rules will improve fuel economy for a typical long haul tractor by 20 percent by 2018.  Meanwhile fuel economy among many vocational vehicles will improve by 10 percent and many work trucks by 15 percent by 2018.

On June 22, 2015, the EPA and NHTSA announced proposed rules for the second phase of fuel economy and greenhouse gas emissions reduction from the heavy-duty fleet.  These proposed rules would apply beginning in 2021 through 2027 and are anticipated to further reduce carbon emissions by another one billion tons while saving 1.8 billion tons of crude oil. Over the lifetime of the proposed rule, diesel is expected to remain the dominant powertrain and fuel. Technologies envisioned to attain the proposed standards will help further advance diesel's well established fuel efficiency credentials. 

Still yet, Phase 1 and the proposed Phase 2 standards together are estimated to reduce greenhouse gas emissions by 1.2 billion tons by 2027.

Read More - While All Eyes are on Phase 2 Let's Not Forget About Phase 1 

While new engines and vehicles are getting cleaner, technologies to reduce emissions from older vehicles are now widely available. Through the use of retrofit upgrades, older diesel engines can improve their performance and reduce key emissions by up to 90 percent. More information on retrofit technology and ongoing programs can be found in the Forum's Online Retrofit Tool Kit.

For additional information about engine certification standards and government regulations, visit the Engine Manufacturers Association (EMA) website.

Phase 1 Clean Diesel Truck GHG Rule Facts


In May of 2010, President Obama, in a Rose Garden Ceremony, announced a new effort to propose greenhouse gas and fuel efficiency standards for medium and heavy-duty trucks and buses and to begin the process for further standards for light-duty vehicles. Then in August 2011, the U.S. Environmental Protection Agency (EPA) and National Highway Traffic Safety Administration (NHTSA) established a national program to reduce GHG emissions and establish new fuel efficiency standards for commercial trucks and buses beginning in 2014 through 2018.

Why is this final rule important?

• It is the first ever regulation of greenhouse gas emissions and fuel efficiency for heavy-duty vehicles. Heavy-duty tractor trailer trucks consume approximately 22 billion gallons of diesel fuel every year, with medium-duty trucks consuming a considerable amount as well. The potential for fuel savings is significant.

What are the medium and heavy-duty trucks subject to this proposed rule?

• More than 95 percent of heavy-duty trucks and a majority of medium-duty trucks are diesel-powered.

• Practically speaking, these are work trucks, ranging from the largest pickup trucks and commercial delivery box vans to "18-wheeler" tractor-trailer type vehicles. Fire and rescue trucks, logging trucks, dump trucks, flat-bed trucks, trucks equipped with cranes and lifts, cement mixers, refrigerated trucks, stake-body trucks, roll-back trucks, cargo and step vans are all examples of the kinds of trucks covered by this rule. The rule establishes specific weight categories for the regulation.  Medium-duty vehicles are those weighing between 8,500 and 10,000 lbs gross vehicle weight according to NHTSA. EPA considers anything over 8,500 lbs gross vehicle weight (GVW) as a heavy-duty vehicle. 

Why haven't these vehicles been regulated before?

• Pursuit of high fuel efficiency has always been a market imperative for this segment. Fuel costs are the first or second highest operating cost of most trucking operations, and the competition for fuel efficiency has always been an integral part of the market.

What is the average fuel efficiency of these vehicles compared to cars?

• Comparing fuel efficiency standard for passenger cars to commercial trucks is not workable and has been acknowledged as such by NHTSA.

• For example, the differences in cars and trucks are many. The vehicles do very different tasks. The typical family car weighs around 2,000 to 4,000 pounds fully loaded. An 18-wheeler weighs about 80,000 pounds fully loaded at the legal federal limit, and the same cab will pull different commodities of different weights.

• An average tractor trailer fully loaded today typically achieves anywhere from 5.0 to 7.0 mpg.

What are the most important aspects of this final rule for manufacturers?

• It is a national program uniform to all 50 states: National uniformity is essential for many reasons relative to the overall feasibility, implementation, cost and acceptance of the program.

• Ample lead time and stability: This is important because the number of commercial trucks made and sold each year (several hundred thousand) is a tiny fraction of the 11-14 million cars made. The significant diversity in the marketplace will require many hundreds, if not thousands, of different approaches depending on the type of vehicle. Manufacturers must have adequate lead time to make changes in technology for this diverse vehicle population along with regulatory stability so that they can recoup their investments over the longer sales and turnover cycles common in this segment.

• It is compatible with the needs and complexities of the diverse marketplace: Commercial trucks encompass a wide range of types, shape and sizes with primary and secondary manufacturers of commercial vehicles, along with many vehicles customized to meet the needs of a broad range of specific work tasks. Efforts to impose fuel efficiency standards should not affect vehicle choice or such efforts could have unintended consequences of causing shifts in the marketplace to less productive and more vehicles on the road.

• Mindfulness of other requirements placed on industry relative to environmental and safety requirements of commercial vehicles: Unlike passenger cars, commercial trucks must adhere to a number of additional federal and state safety and operational requirements. Provisions that impact fuel efficiency must not compromise safety or utility of the vehicle.

• Standards are harmonized to the greatest extent possible: Both EPA and NHTSA are working on these standards and both, as well as other divisions in DOT, have additional authority in regulating this sector. Any future standards should harmonize amongst all federal and state agencies.

Which technologies could be incorporated as a result of this rule?

• Many initial gains in fuel efficiency will be realized through improvements in the efficiency of the diesel engines. This will include further advances in combustion efficiency, waste heat recovery, improved efficiency through advanced turbocharging and fuel injection. Other technologies such as lower rolling resistance tires and aerodynamics, idle reduction strategies and other approaches may also be suitable as a total vehicle approach.

• Some vehicles may be more appropriate for some solutions than others. For example long haul trucks can benefit from aerodynamic improvements that cut vehicle drag and save fuel because they operate at higher average speeds. However local pickup and delivery trucks would not benefit from aerodynamics but would benefit from increased use of hybrid powertrains because of the stop and go nature of their operations.

• Many of the proposed technology solutions are "off the shelf" and the rule advances their wider spread implementation.

Learn more about how More Clean Diesel Trucks Now On the Road Means Lower Fuel Consumption and Fewer Greenhouse Gas Emissions

Diesel Power Dominates Goods Movement

Clean Diesel Progress

The Fleet Owner Guide to Diesel Engines
August 24, 2015 // Fleet Owner

Arranged alphabetically by manufacturer, the following guide offers concise information on engine configuration, displacement, horsepower and torque ranges, and descriptions of engine features and intended applications. Web addresses for additional techni. . .  read more

DTF Launches Learning Series
August 24, 2015 // Mass Transit

Beginning Sept. 2, the Diesel Technology Forum will host a series of online web-based sessions on a range of topics including personal transportation choices, goods movement, rail and water transportation, emergency preparedness, agricultural productivity. . .  read more

Truckers' 2015 fuel tab to fall by $42 billion as oil prices continue sharp decline, group forecasts
August 24, 2015 // DC Velocity

The trucking industry's 2015 diesel fuel bill will come in $42 billion less than 2014's tab due to the decline in oil prices which began last fall and has re-accelerated in recent weeks, according to estimates provided last week by the American Trucking A. . .  read more

Spotlight: Honeywell International

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Become a Member

A growing market for diesel cars, trucks, engines, equipment and fuels is critical to your company's success. A positive media environment and favorable public opinion can reinforce the value of a technology and enable winning public policies. Companies join the Forum because they want to aggressively promote diesel engines, fuels and technology as valuable product and technology solutions for addressing key national priorities.

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