ST PAUL, Minn. — Electric vehicles are zippy, super smart and give off zero emissions, but there's an elephant in the vroom: true battery range.
The estimated battery range for electric vehicles — especially in the cold — is more of a "guess-o-meter," according to one Twin Cities EV expert.
Our cold weather tests in two different Tesla models showed between 37% and 43% fewer miles driven than the estimated range showed.
We wanted to know why the most technologically advanced cars on the road can’t seem to give drivers more accurate range estimates.
Our journey for answers started with a series of tests, first in a Tesla Model Y Long Range and next in a Tesla Model 3 Long Range.
We charged the Model Y at a Supercharger until it read 258 miles until empty (almost a full charge) and drove it from Minnetonka to St. Cloud, a 118-mile round trip of mostly highway driving in 29-degree weather.
For this long-range test, the car dropped 191 miles in the estimated battery range, even though we only drove 118 actual road miles.
Four other shorter tests (under 40 miles) with the Model Y and Model 3 showed similar results. Each trip got between 57% and 63% of the miles estimated on the range gauge.
Next, we wanted to find a warm-weather comparison for the Model Y. We replicated the exact same 118-mile trip to St. Cloud but on an 80-degree day. This time, the car used 21 more miles on the battery than actually driven.
After every trip, the vehicle’s software told us where the car used more energy than estimated — but that does do us any good after the fact.
“I probably lose 30 to 40 percent in the cold,” said Jukka Kukkenon, a former Ford Motor Company engineer who teaches an EV class at the University of St. Thomas and runs an EV consulting business called Shift2Electric. “As long as you are of it, you’re fine, but you have to know about it.”
Kukkenon says it’s no secret that batteries lose their power in cold weather. It’s why combustion-engine car batteries sometimes don’t crank in the frigid temps.
In the case of Tesla, he says the batteries use some of their power to consistently keep the batteries at an optimal temperature in the winter and summer.
The other major factor in frigid weather? The battery's got to keep you warm.
Unlike combustion engines that use a running engine’s wasted heat to warm the cabin, electric vehicles must use battery power to heat a coil and warm the cabin.
The U.S. Department of Energy says about two-thirds of the extra energy consumed in the cold is due to simply heating the cabin.
Again, why don't EVs reflect these facts on your battery gauge?
The U.S. Environmental Protection Agency tests all new car models to produce range and emissions standards for the auto industry.
The agency uses five different tests on all-electric vehicles:
- City test (no HVAC)
- Highway test (no HVAC)
- High-speed test (no HVAC)
- Hot test at 95 degrees (AC used to cool cabin)
- Cold test at 30 degrees (heat used for cabin)
The agency then weighs each test and averages them together to produce a city and highway estimate for mileage on a full battery.
However, we (and several other media outlets) found the weighted average for full electrics doesn’t even come close to the true range in cold weather.
“The car needs to sit in here 12 hours. It has to be at room temperature before you start,” said Paul Steevens, an engineering aid at Minnesota State University-Mankato.
The university has a dynamometer (known as a dyno), which can spin the wheel of a vehicle at various speeds to record how far and efficiently cars can travel.
MSU-Mankato can run the same tests used by the EPA.
“It is efficient at just moving itself, but as soon as you add more [heat] and take it out of those parameters, that range falls way off,” said Steevens.
The EPA says its range tests create “reliable, repeatable and fair” results across all models.
EPA & car company responses
We reached out to Tesla, Ford, Toyota, Nissan and General Motors for comment on their electric vehicles' mileage estimates in cold weather.
Nissan was the only car company to respond.
“Nissan’s official EV range estimates are actually calculated by the EPA, rather than internal Nissan estimates,” said Nissan spokesperson Jeff Wandell. “That being said, yes, it is common to see some range reduction when in cold temperatures. However, Nissan does have some features that help combat this, including a battery heater on vehicles like the LEAF and specific driving modes that help conserve range in certain situations, including cold temperatures.”
A spokesperson for the EPA also responded to a number of questions we asked. Namely, if the EPA would consider offering a warm and cold climate fuel economy label considering how differently EVs perform depending on the temperature.
“The label range is a single number meant to represent the overall average range over the year,” said Shayla Powell with the Office of Public Affairs for the EPA. “No single number can capture the higher range in the spring, summer and fall when temperatures are moderate and then lower in the winter when temperatures are cold. When EPA last considered changes to the fuel economy label, we concluded a single average range result would be more useful to consumers when comparing two vehicles than a list of different ranges for different conditions.”
Given the EPA’s response, and the lack of response from car manufacturers, we don’t expect the fuel range standards to change for EVs anytime soon.
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