Comparison of Aerodynamic Drag Determination Procedures for HDV CO₂ Certification

The European Union and the United States have regulations for the certification of fuel consumption and carbon dioxide (CO₂) emissions from heavy-duty vehicles (HDVs). HDVs have a wide range of configurations and usage, hampering the determination of their fuel consumption and CO₂ emissions by ordinary laboratory techniques. To get around this, the certification processes of the United States Environmental Protection Agency (EPA) and the European Commission (EC) use a combination of simulations and component tests. The simulation suites, GEM in the United States and VECTO in the EU, use component testing to determine the inputs for the simulations. The component tests assess fuel consumption, transmission and axle efficiency, tire rolling-resistance, and vehicle aerodynamic drag. Using the test data, vehicle operation over various drive cycles and loads is simulated. The simulation outputs are the fuel consumption and CO₂ emissions, which are used for vehicle certification. This briefing focuses on the procedures for determination of aerodynamic drag, used for CO₂ certification in the EU and US. The paper describes the tests, data preparation, and calculations used to estimate the aerodynamic drag in GEM and VECTO formats; compares the relative advantages and opportunities for improvement of both procedures; and provides recommendations for other countries planning to implement such procedures.


  • English

Media Info

  • Media Type: Digital/other
  • Edition: Briefing
  • Features: Figures; References; Tables;
  • Pagination: 14p

Subject/Index Terms

Filing Info

  • Accession Number: 01719835
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Sep 9 2019 11:42AM