Part of that, according to Case, is whether the car uses inefficient electric resistance heating or a much more efficient electric heat pump. Heat pumps work like air conditioners, moving heat instead of creating it — so they can be three to four times more efficient than other forms of heating. Recurrent’s data compares cars like the Tesla Model Y — which comes standard with a heat pump — to cars like the Ford Mustang Mach-E, where no models offer a heat pump. According to the study, the Mustang loses almost 30 percent of its range at 20 to 30 degrees Fahrenheit, while the Model Y loses only about 15 percent. “A car with a heat pump does much better when it drops down to freezing than one without,” Case said.