Suggested Citation:
Davies, Jamie (2014) How Assumptions About Consumers Influence Estimates of Electric Vehicle Miles Traveled of Plug-in Hybrid Electric Vehicles: A Review of PHEV Use Data and Possible Implications for the SAEJ2841 Utility Factor (UF) Standard. Institute of Transportation Studies, University of California, Davis, Research Report UCD-ITS-RR-14-03

To characterize the environmental impact and petroleum displacement potential of Plug-in Hybrid Electric Vehicles (PHEVs) it is necessary to know what fraction of travel occurs in each of the two energy use modes. Currently, the Society of Automotive Engineers (SAE) estimates the fraction of US travel a PHEV with a given Charge Depleting (CD) range will electrify based on travel data from a national, single driving day diary and the assumption that PHEVs are charged once per day. This estimate is used by policy makers, transportation researchers and automotive engineers for purposes which range from State Policy (California Zero Emission Vehicle (ZEV) Mandate), battery lifetime estimates, vehicle to grid interactions and other analyses. However, the SAEJ2841 standard is most realistic for instances where its assumptions are valid ; i.e. consumers do not base their PHEV purchase decision on their driving needs, charge once per day at home, don’t have access to or use public charging infrastructure, and drive their PHEV similarly to the vehicle it replaced. This combination of assumptions is only a single use case for PHEVs and represents untested, universal assumptions about how consumers will choose to purchase, drive and recharge PHEVs. We investigate these four assumptions made in the SAE J2841 standard, and compare each one against the best publically available consumer demonstration and academic analyses to begin the process of assessing assumptions and understanding potential implications for analyses or policies which currently use the SAE J2841. Overall, this analysis is meant to bring depth to the discussion of PHEV impacts and policy which seeks to incentivize electric driving.