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GM claims the Chevy Bolt gets 238 miles per charge. Here’s why that’s misleading.

2018 Chevrolet Bolt EV (Chevrolet)
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As the first mass-market vehicle to travel more than 200 miles on a single charge, the Chevy Bolt has quickly become electric royalty.

The vehicle’s mainstream success — which includes being named Motor Trends Car of the Year in 2017 — has quieted skeptics and prompted General Motors to fully commit to an all electric future.

But as automakers like GM tout the increasingly impressive distances their electric vehicles can travel, many consumers may not be aware that peak numbers are heavily dependent upon ideal weather — such as southern California’s warm climate.

The Bolt can travel nearly 240 miles on a single charge, according to General Motors. The company claims some drivers have traveled 300 miles with the same amount of battery power.

But according to driving tests conducted by The Washington Post, that number can easily drop 100 miles or more depending on road conditions, individual driving style and — perhaps most importantly — cold weather.

Despite the disparity in distances, the Environmental Protection Agency — which tests the range of all EVs on American roads — does not dispute GM’s numbers. Yet both GM and the EPA admit that those numbers can vary significantly depending on the outside temperature.

On their website, the EPA says the agency considers their range estimates a “general guideline” for consumers.

“For any electric vehicle, range will always depend on several factors like weather, driving conditions, temperature preferences in the car and overall driver habits,” Joe LaMuraglia, a Chevrolet spokesman, said. “To alert customers of potential range in real time while driving, driver information center includes a confidence gauge, which displays high and low range estimates for the remaining battery life. There are also three in-vehicle energy screens available to monitor energy usage.”

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In colder climates — as many EV drivers quickly learn — low temperatures are the enemy of range. Though they use energy far more efficiently than internal combustion engines, electric motors generate heat more slowly in low temperatures, forcing an EV battery to use some of its own energy to heat the battery and release power, according to the Union of Concerned Scientists, a nonprofit science advocacy organization. But when you combine cold temperatures with abundant heater use, fast driving, quick trips multiple times a day and conventional braking (instead of regenerative), EV range drops even more.

Over the course of several cold weather driving days, a Bolt tested by The Post nearly ran out of power after about 140 miles of driving, nearly 100 miles less than engineers expect from the car under more favorable conditions. That number improved by about 20 miles when the Bolt was driven in a setting that uses regenerative braking, which allows the vehicle to recover electric power each time it slows.

The lower range is not entirely surprising, according to Michael Lelli, the Bolt’s Chief Engineer.

“If the car was aggressively used in very cold weather and never plugged in, then it’s possible you’d see the range decrease the way you did,” Lelli explained after I shared my driving experience with him. “When the weather warms up and heaters are used less and you employ strategies to make the driving more efficient, you’d see the vehicle move back up to the 230- or 240-mile range.”

To put things into perspective: In poor conditions with an inefficient driver, the Bolt’s range still significantly exceeds most of the competition. Nissan, BMW, Kia, Hyundai, Volkswagen, Ford and Honda all have electric vehicles on the market whose top range (under ideal conditions) falls below or barely exceeds the Bolt’s on a bad day.

Bolt engineers accomplished this feat by maximizing the vehicle’s aerodynamics and reducing mass. To reduce mass, Lelli said his team only placed steel in strategic locations and decided to attach the Bolt’s battery to the bottom of the vehicle, making it part of the car’s structure. In addition to giving the car a low center of gravity, that decision made the interior of the car more spacious without increasing mass and harming range.

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For most EV drivers, range anxiety is not an everyday concern, experts say. That’s because EV drivers do more than 80 percent of their charging at home, according to the U.S. Department of Energy. Assuming a driver’s daily commute is less than 200 miles, Bolt owners with access to a home charger are unlikely to experience frequent range anxiety.

But traveling elsewhere — to a new city, for example — can require significant planning, as The Post’s test revealed over the course of two weeks driving the Bolt without access to a home charger in D.C.

Parking garages — where many of the charging stations around town are located — often close after dark. Despite multiple apps showing the location of stations that remain open, finding one under duress can be harder than it sounds. Some garages lack the right type of charger and others appear on the virtual map, but the entrances are difficult to locate in person. On two occasions, garage owners offered quizzical looks when asked if they had an EV power station available.

The answer to challenges like this is to make sure you have access to a home charger and maybe even a separate car for longer distance travel, according to Dan Edmunds, the director of vehicle testing for the automotive website

“The EV is a commuter car, and it’s probably not the car you’d drive on a trip,” Edmunds said. “The ideal EV owner has a couple of cars and a home where they can charge their car a few times a week.”

Edmunds — who regularly drives a 2017 Bolt around Southern California to test its range — said he and his co-workers have traveled about 15,000 miles in the vehicle. So far, he said, the vehicle has averaged just under 250 miles per charge, a number that exceeds GM’s claims. On one occasion, Edmunds said, he traveled 334 miles on a single charge and had enough power remaining in the Bolt’s battery to travel another 15 miles.

“Your mileage may vary in the Bolt,” Edmunds said, “especially if you’ve got cold weather and an aggressive driving style working against you.”

“However,” he added, “in most cases, I’ve found it pretty easy to beat the vehicle’s EPA rated range with a little care, whereas the same level of care in a gasoline car does not often get you the same distance as the rated miles per gallon.”

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