TABLE G-1 History of Heavy-Duty Truck Aerodynamic and Tire Rolling Resistance Coefficients

Truck Configuration Description Cd Crr
Steer Drive Trailer Weighted Averagea
1974 COE T-Tb 1.02 0.0103c
1974 COE T-T, Closed Gap, Trailer Skirts, Boat-Tailb 0.46
EPA Classic Conventional, Exterior Air Cleaners, Verticle Exhaust, Flat Bumber, No Aero Features T-T 0.77
EPA GHG Rule (CE-CERT) 2000’s Conventional High Roof T-T 0.74
EPA GHG Rule Conventional High-Roof Average T-T 0.69 0.0078 0.0082 0.0072d 0.0077
NRC 21CTP, Phase 2, Mid-2000s Conventional High Roof, pre-S/W T-Te 0.63 0.0068
EPA GHG Rule Conventional High-Roof SmartWay T-T 0.59 0.0059 0.0074 0.0053 0.0063
EPA GHG Rule Conventional High-Roof Advanced SmartWay T-T 0.55 0.0055
NRC 21CTP Review, Phase 2, Conventional High Roof, 2015-2020 T-T 0.45 0.0045

NOTE: COE T-T: Cab Over Engine Tractor-Trailer. T-T: Tractor-Trailer. The Cds’ and the Crrs’ in the table are not derived from a consistent set of measurement or test procedures.

a Weightings: Steer (12), Drive (34), Trailer (34) reflect distribution of (80,000) lb Gross Vehicle Weight (GVW).

b K.R. Cooper, Commercial Vehicle Aerodynamic Drag Reduction: Historical Perspective as a Guide, The Aerodynamics of Heavy Vehicles: Trucks, Buses, and Trains, October 15, 2004. Springer.

c Based on bias ply tires.

d Assumed by National Research Council committee.

e Reducing Heavy-Duty Long Haul Combination Truck Fuel Consumption and CO2 Emissions, NESCCAF/ICCT, Miller ed., October, 2009; and Cd same as the DOE 2006 21st Century Truck Roadmap and Technical White Papers. Doc No. 21CTP-003, December, Washington, D.C.

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