Miles per gallon isn’t sophisticated enough; the onset of PHEVs requires new metrics to effectively convey information to consumers. The new metrics are expected to change the way fuel economy estimates are calculated and displayed.
Recognizing the need for these new metrics, Argonne staff assembled a task force in 2006 through the Society of Automotive Engineers. Argonne chaired the committee, whose primary task was to rewrite decade-old test procedures for PHEVs that provide the metrics.
The challenge was to adhere to legacy test standards while properly capturing the fuel and electrical energy use. There were many challenging conflicts to overcome. Between 2006 and 2010, numerous test were conducted by Argonne to help address and solve each challenge faced by the committee.
The revised version of J1711 provides standard test procedures for PHEVs, adding newer test cycles and addressing the expanded design diversity of PHEVs that has occurred since the procedure was originally written. Under the new procedure, all types of PHEVs will be tested in a technology-neutral way with the results designed to quantify potential fuel savings by weighting results according to in-use driving statistics. It is expected that EPA’s certification procedures for PHEVs will draw on much of what is in the J1711 document. Some of the J1711 results are also suitable for use in calculating “Corporate Average Fuel Economy (CAFE) MPG.”