Three facts about EVs and multi-vehicle households – Energy Institute blog
Substitution within households between vehicles could adversely affect the environmental benefits of electric vehicles.
I got interested in how multi-vehicle households use EVs because – from a carbon emissions perspective – we care not only about how many EVs are sold, but how they are used as well. After all, he is not this the manufacture electric vehicles that gives them their environmental advantage is their potential to compensate for driving gasoline and diesel vehicles.
The driving behavior of multiple-vehicle households is particularly important to understand as these households have so many options when it comes to the combination of vehicles they choose to have, as well as the ability to replace multiple vehicles while on the move. I am particularly concerned that this substitution within households will compromise the environmental benefits of electric vehicles. It wouldn’t matter in a future scenario with 100% electric vehicles, but it could matter a lot during a long transition period.
So here are some facts based on the 2017 National road transport survey. I have posted details of all calculations as an Energy Institute working paper here. This is the most recent national representative data. But they are already several years old, and The offerings of the electric vehicle market are evolving rapidly, so I will also discuss later how I think these models will change over time.
Fact 1: 90% of American households with an electric vehicle also own another vehicle.
As the figure below illustrates, only 10% of U.S. households with an EV are single-vehicle households. In contrast, 37% of all US households are single-vehicle households. Thus, households equipped with an electric vehicle are almost four times less likely to be single-vehicle households.
In the United States, it is even common for a household to have more vehicles than drivers. Among American households with an electric vehicle, 36% have more vehicles than drivers, compared to 24% for other American households.
All of this indicates that there is considerable scope for substitution within households. Just because a household owns an EV doesn’t mean it will be the vehicle they’ll use for a family vacation, for example.
Fact 2: 60% of American households with electric vehicles also own a non-electric SUV, truck or van.
The table below describes other U.S. household vehicles equipped with an EV. Cars and SUVs are the most common, but many electric vehicle households also have trucks and minivans. Overall, 60% of households with an EV own a âbigâ non-electric vehicle, that is, an SUV, truck or van.
This model makes a lot of sense. These larger vehicles make it possible to differentiate exterior and interior dimensions, number of seats, cargo space and other attributes. In recent research, economists James Archsmith, Ken Gillingham, Chris Knittel and Dave Rapson find evidence that households substitute between attributes when deciding which vehicle to buy. For example, a household with a fuel-efficient vehicle may be more likely to purchase a second, less fuel-efficient vehicle. This substitution between attributes probably plays a particularly important role with EVs and may help explain why EVs are so popular in multi-vehicle households.
This differentiation is convenient for the household, but it also has implications for fuel economy and gas mileage. These larger vehicles in households equipped with electric vehicles have an average fuel economy of 18.8 miles per gallon, which is lower than the average fuel economy of the US fleet.
Fact 3: 66% of American households with an EV have a non-electric vehicle that runs more.
Finally, two-thirds of households equipped with an EV have another non-electric vehicle that they drive more than kilometers per year. It is somewhat surprising. VE costs less to drive per mile than gasoline vehicles, there is therefore a financial incentive for households to use electric vehicles extensively. It’s not clear why, but there seems to be something in the attributes of EVs that tend to work in the opposite direction.
Whatever the exact explanation, this substitution of driving towards non-electric vehicles reduces the environmental benefits of electric vehicles and provides additional context for previous studies (here and here) who tend to find that electric vehicles are less driven than other types of vehicles.
All of this underlines the importance of the new generation of electric vehicles which includes not only cars, but SUV, trucks, and even this three-wheeled motorhome. The number of EV models available has considerably enlarged and it gives households more flexibility and less need to combine electric vehicles with other non-electric vehicles.
The range is a good example. Earlier electric vehicles had less range than virtually all models available today. The first generation Nissan Leaf, for example, had a range of less than 80 miles, while the current Leaf has a range of over 150 miles, almost double the original version.
In the language of a new paper by Stephen Holland, Erin Mansur and Andrew Yates, this means that electric vehicles are increasingly substitutes for non-electric vehicles, a trend that bodes well for electric vehicles as a climate solution.
Nonetheless, I still think that future research needs to give serious thought to multi-vehicle households. Over the next decade, millions of homes will have both electric and non-electric vehicles, so we need to better understand both how households decide which vehicles to buy and how they decide which vehicles to drive.
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Suggested citation: Davis, Lucas. “Three facts about electric vehicles and multi-vehicle households” Blog of the Institute of Energy, UC Berkeley, September 20, 2021, https://energyathaas.wordpress.com/2021/09/20/three-facts-about-evs-and-multi-vehicle-households/
For more details, see “Electric vehicles in multi-vehicle homesBy Lucas Davis, Energy Institute Working Paper # 322.