Drivers of EVs, like the Hyundai Kona Electric, typically drive less than their gas-powered driving counterparts.

EV owners apparently spend a lot less time behind the wheel than do motorists who drive conventional, gas-powered vehicles, according to a new study – though the exact reason is far from clear.

The study raises a classic chicken-and-egg question: do EV owners drive less because, until recently, most battery-electric vehicles offered relatively limited range, or because their lifestyles involve less travel?

“EVs travel 5,300 miles per year, under half of the U.S. fleet average,” according to a summary of the new study put together for the National Bureau of Economic Research (NBER). Depending upon the source, the general estimate is that the typical American motorist clocks between 12,000 and 15,000 miles annually.

Researchers couldn’t directly access mileage data

The Tesla Model 3 can travel in excess of 250 miles on a single charge – at its lowest rating.

There needs to be an asterisk next to the numbers quoted in the NBER study. Perhaps surprisingly, their data was not gathered by directly surveying EV owners or actually checking their odometers. But such information is difficult to obtain from the automakers who sold the vehicles “due to strategic business interests and privacy concerns.”

So, researchers found an intriguing way to gather the data, by tracking the amount of power used by residential households in California from Pacific Gas and Electric. Next, they parsed the data against registrations for EV ownership between 2014 through 2017. In all, that allowed them to see how much power was used by owners of 57,290 electric vehicles.

Since somewhere north of 85% of BEV owners typically charge up at home or office, this gave the researchers at the Universities of Chicago, California-Davis and California-Berkeley a good sense of how much extra energy was need to keep those battery cars charged up.

And, on average, the total was 2.9 kilowatt-hours per day.

If accurate, EV owners don’t spend much time behind the wheel

The Nissan Leaf’s range started at just 73 miles on a charge and still hasn’t eclipsed 200 miles.

That number could be run through algorithms translating into the average miles per day those vehicles clocked. Without getting bogged down with the math, the final figures translated into 5,300 miles annually.

That figure is substantially less than what many experts had been anticipating. But the project’s unusual methodology is raising some questions about how accurate it really is, with “selection bias” being one of the concerns.

There are other factors to be considered. For one thing, consider the timeframe the NBER studied. By 2017, only a handful of long-range battery-electric vehicles were available to American consumers, starting with the high-priced, relatively low-volume Tesla Models S and X. The more mainstream Model 3 officially went on sale in July 2017, but was produced in low numbers for the rest of the year. The Chevrolet Bolt only came to market in December 2016.

Longer-range EVs could wind up being driven more

Could the potential 500-mile range on the soon-to-arrive Lucid Air change the results of this study in the future?

So, the vast majority of the vehicles likely included in the study were low range, like the original Nissan Leaf or Mitsubishi i-MiEV, yielding less than 100 miles per charge.

While studies show Americans typically commute less than 35 miles per day, other research has suggested that owners of early, low-range BEVs were more likely to have alternative gas or hybrid vehicles available for longer trips or even for running errands when their batteries were run down.

So, it remains to be seen if surveys undertaken now, as the market shifts to products offering anywhere from 200 to 400 miles per charge, yield different results.

Future surveys should aim to include actual, direct mileage data, rather than trying to infer results indirectly, as the NBER numbers might not reflect charging up at the office or the use of the fast-growing network of public chargers.