Diesel Engine Blog – Achates Power

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Heavy-Duty Truck Fuel Efficiency and GHG Emissions Standards

Wallace Wade, Retired Ford Technical Fellow, Ford Motor Companyby Wallace Wade
Retired Ford Technical Fellow
Ford Motor Company

Heavy-duty trucks are the fastest growing contributors to greenhouse gas (GHG) emissions within the
transportation sector, producing nearly 20 percent of GHG and accounting for 17 percent of transportation oil consumption. Because of this, the U.S. Energy Independence and Security Act (EISA) of 2007 directed the National Highway Traffic Safety Administration (NHTSA), in consultation with the Department of Energy (DOE) and the Environmental Protection Agency (EPA), to study the fuel efficiency of heavy-duty trucks and to implement, for the first time ever, fuel-efficiency standards for these vehicles.
On September 15, 2011, following a Notice of Proposed Rule Making issued in November 2010, the EPA and NHTSA issued final “Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles” that will begin with model year 2014. The new standards, which will be phased in, apply to model years 2014-2018 and are tailored to each of three main regulatory categories of vehicles:

  • Combination tractors, commonly known as semi-trucks that typically pull trailers (Class 7 and 8), although the agencies are not regulating trailers;
  • Vocational vehicles, which comprise a very wide variety of truck and bus types (Class 2b through 8); and
  • Heavy-duty pickup trucks and vans (Class 2b and 3).

Incentives are provided to encourage the introduction of advanced technologies, including hybrid powertrains in appropriate applications. In addition to controlling CO2 as a greenhouse gas emission, the EPA rules also cover hydrofluorocarbon standards to control leakage from air conditioning systems in combination tractors, pickup trucks and vans, and nitrous oxide (N2O) and methane (CH4) emissions standards that apply to all heavy-duty engines.
The standards for vocational vehicles and combination tractors have separate fuel-consumption standards for vehicles and for engines. Fuel-consumption standards for tractors are expressed in gallons per 1,000 ton-miles (based on tons of freight hauled) and in gallons per 100 bhp-hr for engines. By model year 2018, these standards will require up to a 23 percent reduction in fuel consumption and CO2 emissions relative to the 2010 baseline.
The standards for vocational trucks (Class 2b through 8) are also expressed in gallons per 1,000 ton-miles and are set separately for light heavy-duty (Class 2b through 5), medium heavy-duty (Class 6-7), and heavy heavy-duty (Class 8) trucks. Achieving standards for vocational vehicles is limited to engine improvements and tire technologies for reduced rolling resistance. By model year 2018, the standards for vocational vehicles will require up to a 10 percent reduction in fuel consumption and CO2 emissions compared to the 2010 baseline.
The standards for heavy-duty pickups and vans (Class 2b and 3) are expressed in gallons per 100 miles with separate standards for gasoline-fueled and diesel-fueled vehicles. The EPA and NHTSA expect industry to apply similar technologies as the 2012-2016 light-duty vehicle CAFE program, but adapted to heavy-duty applications. The standards are fleet-wide corporate average standards as in the case for light-duty vehicles. By model year 2018, the standards will require an average per-vehicle reduction in fuel consumption and CO2 emissions of up to 15 percent for diesel and 10 percent for gasoline vehicles compared to a common 2010 baseline.
Over the lifetime of heavy-duty vehicles built for model years 2014-2018, these standards, if successfully met, will promote improvements to overall efficiency that are expected to result in a savings of 530 million barrels of oil and a reduction of 270 million tons of carbon emissions. Achieving these reductions will improve national energy security, reduce air pollution and benefit consumers and businesses with lower costs for transporting goods while spurring innovation in the clean energy technology sector.

  • Gary Schneweis says:

    I bought my first diesel p/u in 1996 and have had many since. i know the hp and torque have doubled but the fuel economy is 30% less on newer diesels. How is consuming more energy better for enviroment, we are drilling more or importing more oil. i have friends that run trucking companies and they all say that between 1998 and 2001 engines are the most fuel efficent engines they ran,so how are we better? I feel we are going backwards!

    January 27, 2012 at 5:18 pm
    • Brian says:

      Gary –
      I, too, have experienced the same thing and had the same conversations with other farmers in my area. The trucks have worse fuel efficiency, not better. I have a 2001 and a 2009 diesel. I will warn you about the newer trucks. If you live in a rural area where the dealership is not nearby, you will not be happy.
      The new exhaust aftertreatment systems on the trucks are horrible. They have to be cleaned often, and I find myself making a 160 mile roundtrip trek to the dealership in the city just to have it cleaned every 4 months. It will leave you on the side of the road if you aren’t careful. A neighboring farmer put his off about two months too long and ended up with $18,000 in damage – burned up the turbo, injectors, and a lot more. The exhaust systems don’t let the engine breathe – it reduces fuel efficiency, hp, and torque – drags the whole engine down til it burns up or you take it in for cleaning.
      The 2001 truck is still running just fine and has much better fuel efficiency, especially when towing the cows to town.
      I don’t know what the solution is. It would be nice if I could drive a Volt, but I don’t think it’d haul the animals or have enough room in the trunk for feed and hay…

      March 29, 2012 at 12:21 am
      • Larry Fromm says:

        All of the truck manufacturers that Achates Power is working with are putting significant effort into enhancing overall powertrain performance and balancing service intervals and reliability while meeting strict emission mandates, improving fuel economy, and keeping costs as low as possible. Some of the aftertreatment equipment is relatively new, so we will see rapid improvement. We expect to be part of the overall solution, since our opposed-piston engine is more efficient and lower cost with clean combustion that can be configured to reduce loading of the diesel particulate filter.
        Despite the problems you describe, it is hard to beat diesel engines for the best combination of power, fuel economy, price, durability, range and refueling convenience.
        Larry Fromm
        Vice President, Business and Strategy Development
        Achates Power

        March 30, 2012 at 12:09 pm
  • Wallace Wade says:


    Many factors affect the fuel economy realized by customers.

    One of these factors is the fuel efficiency of the engine. Some diesel engine manufacturers have reported the fuel efficiency of their engines over the years. These data show improving fuel efficiency through the year 1999. Then as emission standards were significantly tightened through 2004, fuel efficiency deteriorated. As exhaust aftertreatment systems were applied to meet even more stringent emission standards, fuel efficiency again started showing improvements by 2010. Emissions have been reduced by 98% since 1988, with nearly no net change in fuel efficiency, a remarkable achievement.

    As noted, heavy-duty diesel pickup manufacturers have nearly doubled the horsepower and torque output of their diesel engines since the mid-1990s. These increases have been driven by customer demands for increased vehicle size and weight, increased cargo loads, increased trailer towing capacity, more power consuming accessories, and higher performance. All of these factors affect customer fuel economy.

    NHTSA and EPA have issued, for the first time ever, fuel efficiency standards for heavy-duty trucks, which include heavy-duty gasoline and diesel pickup trucks over 8500 pounds gross vehicle weight rating (GVWR) for model years 2014-2018. By model year 2018, the standards will require an average per-vehicle reduction in fuel consumption of up to 15 percent for diesel pickup trucks compared to a common 2010 baseline.


    January 31, 2012 at 11:35 am

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