A new study by Consumer Reports reveals that the driving range of electric vehicles including Teslas can be cut in half during winter months in cold climates.

A study published by Consumer Reports has revealed that the driving range of Tesla’s cars and electric vehicles is seriously diminished by cold climates; something which many owners discovered recently during the polar vortex which hit parts of the United States. The report used two different brands of electric vehicles, one Tesla Model 3 and one Nissan Leaf, to compare how they both reacted to extremely cold weather.

Jake Fisher, the senior director of auto testing at Consumer Reports, commented on the company’s findings stating: “Typically, we warn new-car shoppers not to buy more vehicle than they need, whether that’s seats, cargo room, or towing capacity. But in this case, EV buyers who drive in colder climates should strongly consider getting a car with a range about double what their daily driving needs are, so they’re not left stranded in a cold snap.”

For the experiment, CR drove the two electric vehicles on multiple trips in one day during the cold weather of January this year. Temperatures at the Connecticut testing track where the experiment took place reached between 0 and 10 degrees at the time of the test. The results of the testing show:

The Nissan Leaf (with its base 40 kWh battery; a longer range version is set to go on sale later this year, Nissan has said) has an Environmental Protection Agency-estimated 151-mile range. At the end of our 64-mile drive, the predicted range left was only 10 miles. Using the advertised range, the car should have traveled 141 miles before it was left with only 10. That’s more than double the anticipated loss in range. The Tesla Model 3 has an EPA-estimated 310-mile range. At the end of that same 64 mile drive, it indicated there were 189 miles of predicted range. Put another way, the Model 3 used 121 miles worth of range in only 64 miles. That’s almost double the anticipated loss.

Sam Abuelsamid, a senior analyst at automotive research and consulting firm Navigant, explained why electric vehicle batteries appear to drain so rapidly in cold climates stating: “Unfortunately, cold temperatures will always have a negative impact on range… Breathing means condensation on cold glass, which requires use of electric defoggers. Longer nights mean more use of headlights. And cold tires, snow, and slush will increase rolling resistance, all of which will reduce range.”

Abuelsamid notes that traditional gas-powered cars also suffer decreased performance in cold weathers stating: “Sadly, no matter how sophisticated your software is, Mother Nature and physics will always win out in the end.”

Read the full study by Consumer Reports here.