A resistive PTC heater turns electricity into heat one-for-one, and in a hard frost it can draw several kilowatts, energy that would otherwise be range. A heat pump moves heat rather than making it, so above about −5 °C it delivers the same cabin warmth for well under half the electrical draw.
Our model treats the two heater types differently, which is why a heat-pump car shows a smaller winter range drop than an otherwise-identical PTC car. Below about −5 °C the heat pump's advantage fades toward resistive levels, and we model that too.
Check the winter range card and temperature curve on each car page, heat-pump cars hold up visibly better in the cold. The exact HVAC model is on the methodology page.