Analysis of the US procedure for the fuel consumption and greenhouse gases certification of heavy duty vehicles

Abstract: The vehicle sector is facing the biggest revolution of the last 70 years, whose main target is the depletion of emission and a steady decrease of fuel consumption. The focus in this report is the Green House Gas Emissions model (GEM) developed by the United States Environmental Protection Agency (EPA). The model is one of the newest and most complete simulation tool aimed to provide estimation of fuel consumption and CO2 emissions for the US market depending on the input inserted and the type of vehicle chosen. The usage of these tools is expected to increase in the next decades as it presents a more economical solution compared to chassis dynamometer and real driving test. Furthermore, all the environmental agencies that are developing these programs play also a key role in establishing new rules and regulations. Scania, as one of the leading manufacturer companies of heavy duty vehicle worldwide, needs to learn about the new certification processes in US to be able to expand in this specific market. The aim of this work is to learn more about the GEM and to validate its results. A theoretical review is performed to understand how GEM is working and how each parameter could possibly affect the outcomes. Several parameter variations on a long haulage HDV are performed with the GEM and output results presented. To validate the GEM the European simulation tool VECTO and an internal Scania worksheet for fuel consumption and emissions analysis are used as they were previously validated by means of the chassis dynamometer test.  GEM shows very similar results in this comparison with VECTO and the internal Scania worksheet. Assessing the reliability of this programme on a larger scale could represent a key aspect for Original Equipment Manufacturers (OEMs) as they could use this simulation tool to easily and rapidly have some fuel economy results solely based on the specifications of the vehicle in analysis.