UC Davis Institute of Transportation Studies

Vehicles that can run on both electricity and gasoline—so-called plug-in hybrid electric vehicles (PHEVs)—are proposed as both a near-term technology to achieve energy and environmental goals and a transitional step toward viable all-electric vehicles addressing many of the same goals. Whether PHEVs meet any of their goals depends not only on their design and performance on standardized drive cycles, but also on drivers’ travel and refueling/recharging behaviors. To replace assumptions with observations of potential PHEV drivers’ behavior in market and impact analyses, we conducted an internet-based survey of 2,373 new car-buying households in the United States. The instrument was implemented in three separate pieces, requiring multiple days for households to answer questions, conduct a review of their own driving and parking patterns, and then complete a sequence of PHEV design exercises. In this paper, we draw five conclusions from the resulting data. First, most new vehicle buyers are unaware of PHEVs in particular and are confused about electric-drive terminology commonly used by experts. Second, at least half of our target population is already equipped for at-home vehicle recharging, but currently have little opportunity for recharging at their workplace or other locations. Third, we observed widely varied interests in four possible PHEV attributes—fuel economy in both charge-depleting (CD) and charge sustaining (CS) operation, blended vs. all-electric operation, the distance over which the vehicle is in CD mode, and recharging speed. Still, the appeal of increased fuel economy appears to be highest and that of faster recharging to be lowest. Further, there is little interest in all-electric operation. Fourth, given the previous two points, we estimate that about a third of the target population has both the infrastructure to recharge a PHEV and interest in a vehicle with plug-in capabilities. Fifth, our recharge scenarios demonstrate that although widespread PHEV use could halve gasoline use, impacts to the electricity grid could highly depend on the time-of-day and location recharge management strategy. While unconstrained recharging among PHEV buyers may exacerbate current peak electricity demand, pushing vehicle recharging to off-peak hours through charging controls, time of day tariffs or other means could reduce overall electricity used by vehicles. Overall, policy, technology, and energy providers may use this information to understand whether their plans, designs, and goals align with these present understandings, or whether it would be collectively beneficial to foster new understandings of PHEVs among U.S. carbuyers.