The total fuel and energy consumption rates of a Plug-In Hybrid Electric Vehicle (PHEV) vary depending upon the distance driven. For PHEVs, the assumption is that operation starts in battery charge-depleting mode and eventually changes to battery charge-sustaining mode. Total distance between charge events determines how much of the driving is performed in each of the two fundamental modes. An equation describing the portion of driving in each mode is defined. Driving statistics from the National Highway Transportation Survey are used as inputs to the equation to provide an aggregate "Utility Factor" (UF) applied to the charge-depleting mode results.
Various stakeholders are currently developing their own standards for testing PHEVs. The method of weighting the results using a UF is accepted by many of the stakeholders. However, the stakeholders need a standard document to reference in their procedures. These curves must be from a common standard generated from a standardized calculation method. SAE J1711 will reference this document and as new and/or better data become available, this Information Report may be updated without changing the SAE J1711 or other stakeholder procedures.