Rethinking VMT: Factors affecting household VMT focusing on differences between ICEVs and EVs

This study examines factors affecting household vehicle miles traveled (VMT) with a focus on the differences between electric vehicles (EVs) and conventional internal combustion engine vehicles (ICEVs). This study mainly utilizes detailed individual-level data from the 2017 National Household Travel Survey-California Add-on (2017 NHTS-CA). We first classify households into three groups such as 1) households with only ICEVs, 2) households with only EVs, and 3) households with both ICEVs and EVs. We then employ OLS regression models to analyze the determinants of household VMT across three groups. Second, we focus on households with both ICEVs and EVs to look at the substitute patterns between ICEVs and EVs. We employ the Seemingly Unrelated Regression (SUR) model to analyze total household VMT and its distribution among ICEVs and EVs. Some key findings are as follows. First, households with only EVs tend to have lower household VMT than others. Second, available EV charging stations near residential locations lead to longer households VMT in households with only EVs. Third, employment density has different effects on household VMT by groups. For instance, high employment density leads to shorter household VMT in households with only ICEVs and with both ICEVs and EVs. On the other hand, high employment density reveals a statistically positive effect on household VMT in households with only EVs. Lastly, in households with both ICEVs and EVs, the share of EV VMT is likely to increase in total household VMT if EVs are used more for work trips and shopping/family errands.