Maybe stating the obvious here, but the largest part of those savings will have been tailing the truck
To put this into perspective, a little math!
My car still has the old resistive heater - so all the heat energy that goes into the cabin is straight electricity from the battery. In winter (lets say ~5°C, lolwinterright?) when starting the drive, this resistive heater will pull its full 6 kW for a few minutes and then settle down once temperature is reached to maintain 20°C inside (I almost never touch this setting), which will result in an average power draw of about 1.2-1.5 kW. For the sake of easy math, let's assume avg 100 km/h, this would mean my average comsumption would go from about 16 kWh / 100 km to 17.5 kWh / 100km.
With a heat pump, one could realistically assume a COP of 3 (coefficient of performance - since "efficiency" should theoretically be below 100%). Thus, the power need for inside heating would drop from 1.5 kW to 0.5 kW. Meaning, for my example, I'd run 16.5 rather than 17.5 kWh / 100 km. It's definitely noticeable alright, but quite far from the improvement you've seen tailing that truck
edit: I'm assuming the ioniq will lose the same amount of heat through doors, windows and body as my t3 - although it's probably much better insulated, really. but then again, the magnitude of things doesn't change all that much (whether its 500 or 400 W, who cares) and a COP=3 at really low temperatures is quite generous.
To put this into perspective, a little math!
My car still has the old resistive heater - so all the heat energy that goes into the cabin is straight electricity from the battery. In winter (lets say ~5°C, lolwinterright?) when starting the drive, this resistive heater will pull its full 6 kW for a few minutes and then settle down once temperature is reached to maintain 20°C inside (I almost never touch this setting), which will result in an average power draw of about 1.2-1.5 kW. For the sake of easy math, let's assume avg 100 km/h, this would mean my average comsumption would go from about 16 kWh / 100 km to 17.5 kWh / 100km.
With a heat pump, one could realistically assume a COP of 3 (coefficient of performance - since "efficiency" should theoretically be below 100%). Thus, the power need for inside heating would drop from 1.5 kW to 0.5 kW. Meaning, for my example, I'd run 16.5 rather than 17.5 kWh / 100 km. It's definitely noticeable alright, but quite far from the improvement you've seen tailing that truck
edit: I'm assuming the ioniq will lose the same amount of heat through doors, windows and body as my t3 - although it's probably much better insulated, really. but then again, the magnitude of things doesn't change all that much (whether its 500 or 400 W, who cares) and a COP=3 at really low temperatures is quite generous.