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(MONDAY) Is the rebound effect symmetrical? Evidence from households shift away from EVs
The global transition toward EVs has accelerated in recent years, driven by stringent regulations and ambitious EV adoption targets aimed at mitigating greenhouse gas emissions. As EVs become an increasingly dominant part of the transportation landscape, understanding their broader implications on household behavior and energy use is essential. Among these considerations, the rebound effect- the increase in VMT due to the reduced usage costs of EVs- has drawn significant attention. Critics argue that this effect could offset some of the anticipated environmental benefits of EV adoption, raising concerns about the true efficacy of electrification policies.
While much attention has been given to the potential rebound effect associated with increasing energy efficiency (Sorrell et al., 2009; Gillingham et al., 2013; Steren et al., 2022), an equally important yet overlooked question is what happens when households transition away from EVs to less efficient vehicles. This shift is not just a theoretical concern but a growing trend: As more households experiment with PEVs, a significant subset chooses to revert to ICEVs or less efficient vehicles. For example, Hardman and Tal (2021) found that PEV discontinuance rates reach 18.1% for BEVs in California. A common assumption in energy economics is that changes in mileage are symmetric – households drive more when usage costs decrease and reduce their mileage proportionally when costs rise. However, if the response to efficiency losses is stronger than the response to efficiency gains, it suggests that households adjust their behavior differently when facing increased costs compared to when they experience savings. Recognizing these dynamics can help to better anticipate behavioral responses and improve the effectiveness of fuel efficiency regulations.
To investigate these dynamics, we use household-level panel data from five questionnaire surveys conducted between 2015 and 2019. These surveys targeted households in California that had purchased a PEV. Our analysis focuses on two distinct household groups: (1) those transitioning from an efficient plug-in vehicle to a less efficient vehicle, and (2) those shifting from a plug-in vehicle to a more efficient one. By comparing changes in VMT across these groups, we estimate the rebound effect, defined as the elasticity of VMT in response to changes in vehicle efficiency (in MPG).
Preliminary results suggest that, on average, households that switched to a more efficient vehicle (MPG = 94.1) exhibited a modest 4% rebound effect, meaning they increased their VMT slightly in response to improved fuel economy. In contrast, households that switched to a less efficient vehicle (MPG = 42.7) demonstrated a 15% rebound effect, suggesting a more pronounced behavioral response to reduced efficiency. These findings suggest that households respond asymmetrically to efficiency changes, with those facing higher fuel costs reducing travel more significantly than those benefiting from lower fuel costs. While these results are preliminary, they highlight the need for further investigation into how efficiency shifts impact overall travel demand.
Our findings suggest that reductions in efficiency lead to a disproportionately large decrease in VMT compared to the increase observed when fuel efficiency improves. Understanding these behavioral patterns can help refine emissions modeling and better estimate the actual environmental benefits of vehicle efficiency policies.
(TUESDAY) Understanding the Electrification Potential of Class 2b-3 Vehicles:
Insights from Vehicle Registration Data in California
Medium- and heavy-duty vehicles (MHDVs) contribute 20.6% of California’s transportation-related emissions, emphasizing the urgent need to decarbonize this sector (Brown et al., 2021). Among these, class 2b-3 vehicles, weighing 8,501–14,000 lbs., form a significant and unique market segment that bridges light-duty passenger vehicles and heavy-duty commercial trucks (Lutsey, 2015). Representing over half of MHDV sales in the U.S., these vehicles are critical targets for electrification, yet they remain underexplored in academic research and policy discussions (Mulholland, 2022; Birky et al., 2017). This study leverages robust vehicle registration data to examine the characteristics, usage patterns, and electrification potential of class 2b-3 vehicles, with a focus on identifying disparities in adoption and operational efficiency across geographic and demographic segments. Unlike previous studies that primarily focus on commercial fleets or larger truck classes, this research investigates vehicles operated by households for both personal and business purposes, offering novel insights into this market segment.
This study analyzes comprehensive 2022 DMV registration data covering all vehicles in California, integrating it with DataOne vehicle specifications to classify class 2b-3 vehicles based on regulatory definitions. Statistical tests are used to examine geographic distribution, ownership patterns, and operational characteristics, providing insights into adoption trends, usage patterns, and efficiency differences across regions and vehicle types. Further analysis will be presented at the conference to explore the underlying drivers of these trends in greater depth.
Preliminary findings suggest significant geographic disparities in the concentration of class 2b-3 vehicles. Northern and rural counties, such as those in the northernmost regions of California, exhibit higher concentrations of these vehicles compared to urbanized southern and coastal areas. A comparison of class 2b-3 vehicles with heavy light-duty trucks (HLDTs) reveals parallel trends in gross vehicle weight over time. However, in terms of vehicle footprint (which is calculated using the track width and wheelbase, then adjusted to square feet), class 2b-3 vehicles display an increasing trend, contrasting with the relatively constant footprint of HLDTs. Vehicle usage patterns further highlight the distinct characteristics of class 2b-3 vehicles. While HLDTs have slightly higher mileage during their first seven years of operation, a trend reversal occurs after this period, with class 2b-3 vehicles gaining mileage more rapidly. Efficiency trends also diverge between the two segments. Over the past decade, HLDTs have demonstrated a 43% improvement in efficiency, compared to a more modest 24% increase for class 2b-3 vehicles. Despite this, both categories exhibit an increasing trend in the share of electric vehicles (EVs), with 4.5% of 2b-3 vehicles and 7% of HLDTs now being electric.
This study is among the first to provide a comprehensive, data-driven analysis of the class 2b-3 vehicle market. By combining rich registration data with advanced econometric techniques, the research identifies key barriers to electrification and highlights emerging trends in vehicle efficiency and adoption. The findings offer actionable insights with implications for designing targeted incentives, aligning regulatory frameworks, and accelerating the electrification of medium-duty vehicles."
