FIGURE 5-1 Aerodynamic and tire power consumption for tractor-trailer combination. SOURCE: NESCCAF/ICCT (2009).


The goal of the 21CTP is to conduct research, provide hardware demonstrations, and validate and deploy cost-effective, reliable, and durable technologies that reduce vehicle power demands. The Partnership will continue to utilize a vehicle system approach to continually track the benefits of individual technologies on overall vehicle efficiency and performance. Five primary technology goals applicable to the target tractor-trailer truck are to be achieved over the next 10-year period (DOE, 2011).

1.   Goal 1 (reference level of 53 percent aerodynamic power consumption): Reduce the aerodynamic drag coefficient by 20 percent (from a Cd of 0.69). Evaluate a stretch goal of 30 percent reduction in aerodynamic drag. (The baseline is from the Environmental Protection Agency/National Highway Traffic Safety Administration [EPA/NHTSA] final rule “Greenhouse Gas Emissions Standards and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles” for a conventional Class 8 tractor with high-roof sleeper. [EPA/NHTSA, 2011; NRC, 2010].) (Also, see footnote 3 in this chapter.)

2.   Goal 2 (reference level of 32 percent rolling resistance power consumption): Reduce tire rolling resistance by 35 percent from tractors equipped with dual-tire drive wheels. (The baseline Crr is 0.0082 from the EPA/NHTSA rule for tires of the dual tire drive wheels, only, of a Class 8 tractor [EPA/NHTSA, 2011; NRC, 2010].) (Also, see footnote 3 in this chapter.)

3.   Goal 3 (reference level of 9 percent auxiliaries’ power consumption): Reduce essential auxiliary loads by 50 percent. (The baseline for this goal is a Class 8 highway tractor-trailer with sleeper, operating 5 days in over-the-highway operations at 80,000 lb gross combined vehicle weight [GCVW].)

4.   Goal 4: Reduce tare weight by 10 percent, and for the long-term stretch goal by 20 percent, from a 34,000 lb base tractor-trailer capable of an 80,000 lb GCVW operation, and comprised of a tractor (19,500 lb), trailer (13,500 lb), and fuel (1,500 lb).

5.   Goal 5: Thermal Management, and Friction and Wear Reduction

a.   Thermal Management Systems: Increase heat-load rejected by 20 percent without increasing radiator size.

b.   Friction and Wear (reference level of 6 percent drivetrain power consumption): Reduce powertrain and drivetrain consumptions by 50 percent (NRC, 2010).4

The committee appreciates these carefully formulated goals statements. The committee believes that these goals are achievable within the 10-year period specified, but only if adequate research and development efforts are expended. Typically, achieving some goals will be found more problematic than achieving others. In the more problematic


SmartWay brand identifies products and services that reduce emissions, such as greenhouse gas emissions. Certification using EPA test methods allows carriers, manufacturers, and shippers to apply the SmartWay logo. See the EPA website at and NRC (2010) for more detailed information.

4 Notes to Goals 1 and 2 were prepared to compare these current numerical goals to those stated in the DOE (2006) White Paper Roadmap, as well as to compare certain Cds and Crrs corresponding to other frequent descriptions (current available, SmartWay, Advanced SmartWay). See Appendix G in this report. The baseline for these goals is a Class 8 highway tractor-trailer with sleeper operating at a steady 65 mph at 80,000 lb GCVW.

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