Analyzing the Uncertainty in the Fuel Economy Prediction for the EPA MOVES Binning Methodology

Developed by the U.S. Environmental Protection Agency (EPA), the Multi-scale mOtor Vehicle Emission Simulator (MOVES) is used to estimate inventories and projections through 2050 at the county or national level for energy consumption, nitrous oxide (N₂O), and methane (CH₄) from highway vehicles. To simulate a large number of vehicles and fleets on numerous driving cycles, EPA developed a binning technique characterizing the energy rate for varying Vehicle Specific Power (VSP) under predefined vehicle speed ranges. The methodology is based upon the assumption that the vehicle behaves the same way for a predefined vehicle speed and power demand. While this has been validated for conventional vehicles, it has not been for advanced vehicle powertrains, including hybrid electric vehicles (HEVs) where the engine can be ON or OFF depending upon the battery State-of-Charge (SOC). The Powertrain System Analysis Toolkit (PSAT), a vehicle simulation software developed by Argonne National Laboratory, will be used to generate the MOVES bins as well as evaluate the uncertainties. This paper will quantify and explain the fuel economy uncertainties introduced by the “average” vehicle in the representative source bins for several powertrain configurations, control strategies, and drive cycles defined in MOVES.