Winter range loss is real and physical, not a fault. Three things stack up in the cold: the cabin heater draws power the battery would otherwise spend on miles; air is denser when it's cold, so aerodynamic drag rises; and the battery itself is less willing when cold.
Our model computes each of these separately. A resistive PTC heater can pull several kilowatts in a hard frost; a heat pump typically does the same job for well under half the energy above about −5 °C, which is why heat-pump cars lose less in winter.
Rather than a single scary percentage, every car page shows a winter range card and a range-vs-temperature curve for that exact model, adjusted for its battery health. See how we work it out.