TABLE 5-1 Energy Audit—Baselines and Targets (80,000-lb Gross, 65-mph Level Road)

Goal/Technical Area




Improvement (percent)

Primary Technology Goals

Goal 1: Aerodynamic losses

85 kW/114 hp

68 kW/91 hp

17 kW/23 hp


Goal 2: Auxiliary loads

15 kW/20 hp

7.5 kW/10 hp

7.5 kW/10 hp


Goal 3: Reduce tare weight

12,245 kg/27,000 lb

9,795 to 10,410 kg/21,600 to 22,950 lb

1,837 to 2,450 kg/4,050 to 5,400 lb

15 to 20

Other Technology Goals

Goal 4: Thermal management and friction and wear

Goal 4a: Waste heat rejection

Increase in cooling heat rejection by 20 percent without increasing radiator size.

Goal 4b: Powertrain losses

9 kW/12 hp

4.5 kW/6 hp

4.5 kW/6 hp


Goal 5: Rolling resistance

10 percent reduction relative to existing best in class

SOURCES: DOE, 2000; DOE, FCVT, 2006.

around heavy truck vehicles using existing and advanced computational fluid dynamics (CFD) tools. The final products are validated CFD tools that can be used to reduce aerodynamic drag of heavy truck vehicles and thus improve their fuel efficiency.

The team included participants from DOE national laboratories, universities, and the National Aeronautics and Space Administration (NASA). Visits were made to truck and trailer manufacturers to get their views on the issues to overcome in order that lower drag heavy vehicles would be commercially viable. Workshops were held and reports on the work of the various participants were issued on a regular basis through 2005. These reports are available at the DOE Scientific and Technical Information web site.1 In each working group report the project goals were reaffirmed in the following form through 2003 (with some variation in the items listed in parentheses in the last line):

  • Perform heavy vehicle computations to provide guidance to industry

  • Using experimental data, validate computations

  • Provide industry with design guidance and insight into flow phenomena from experiments and computations

  • Investigate aero devices (e.g., boattail plates, side extenders, …)

In the report of the July 2004 meeting of the working group (the last line was changed as follows including the bold type for the last part of the statement).

  • Investigate aero devices with emphasis on collaborative efforts with fleet owners and operators.

The reports for 2005 reaffirm this statement of goals. Reports on the work on aerodynamic drag from 2006 appear in a different form as parts of the annual progress report of the Heavy Vehicle Systems Optimization Program (DOE, FCVT, 2005a) and the 2000 Heavy Vehicle System Review (NRC, 2000a).

The work began, as the goal statement reflects, with a primary focus on computational tools and with experiments expected to serve the purpose of supporting the computational tool developed, as opposed to the experimental program being a parallel path for development of drag reducing design features. The computational tools on which the majority of resources were expended were codes that had their origins at the national laboratories. By 2001 a number of truck manufacturers were invited to the working group meetings and made presentations on their approaches to aerodynamic development. The principal manufacturers all had small in-house teams who had a history of doing experimental development in wind tunnels and who had recently begun evaluating and using commercial computational fluid dynamic (CFD) codes. Although the truck manufacturers were somewhat interested in the claims of the team about the potential power of their CFD codes, their opinion was that the only way the features would become feasible for industry use would be if the features were incorporated into commercial codes that would be accessible to all and maintained for customers over time.

The DOE heavy vehicles team organized a conference on the aerodynamics of heavy vehicles (DOE, 2004). Kevin Cooper of the National Research Council, Canada, gave the keynote paper, “Commercial Vehicle Aerodynamic Drag Reduction: Historical Perspective as a Guide” (Cooper, 2004). Cooper gave a concise history of prior work on truck aerodynamics and demonstrated that data were already available to allow assessment of the potential of a number of drag reducing devices including tractor-trailer gap closure, trailer skirting, and boat-tailing, and had been available for several


Available at

The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement