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Aerodynamic drag testing is a key component of the CO2 certification schemes for heavy-duty vehicles around the world. This paper presents and compares the regulatory approaches for measuring the drag coefficient of heavy-duty vehicles in Europe, which uses a constant-speed test, and in the United States and Canada, which use a coastdown test. Two European trucks and one North American truck were tested using the constant-speed and coastdown methods. When corrected to zero yaw angle, a difference of up to 12% was observed in the measured drag coefficients from the US coastdown procedure and the EU constant-speed test.

This analysis is a comprehensive assessment of the fuel-saving technologies and technology packages for three representative diesel HDV types in India: a 40-tonne Gross Vehicle Weight (GVW) tractor-trailer, 25-tonne rigid truck, and a 16-tonne transit bus. These representative vehicle types are modeled after top-selling models in the Indian market based on sales data from fiscal year 2013-14. To model these vehicle types are accurately as possible, the study team acquired detailed engine maps that match the engine models in the respective vehicles and sought input on other vehicle systems from some of the leading Indian HDV manufacturers and suppliers. Using Autonomie as the vehicle simulation platform, the authors investigate the fuel consumption impacts of both individual technologies and combinations of technologies in the following areas: engine, transmission, driveline, aerodynamics, tires, material substitution (i.e., curb weight reduction), and hybridization.