Very unscientific test. - I have a LR AWD Model 3 currently running on the 18” Aero winter package. - Most mornings I do the same drive - first I drive my son to school, and then I head down to work. The drive from my son’s school to my office in downtown Toronto is apx. 17.6 km (just shy of 11 miles) and is probably net downhill. I also keep the HVAC on manual, fan speed at 2, and temp at 18.5 C (65.3 F). - I didn’t drive last Friday but I did on Thursday and the weather was very similar to this morning. Dry and about 4 degrees Celsius (apx 39 degrees F). - Driving relatively conservative, I typically can get to an average of about 215- 220 wh/Km on the way down to the office (apx 354 wh/mile). - This morning, the only difference was I turned off the HVAC entirely and set the seat heaters to the 2nd level. -It definitely was getting uncomfortably “cool” in the car, and the windows (side and rear especially) were becoming quite foggy. But...I ended up pulling into parking with the trip meter showing 119 wh/km! (17.6 km, 37 minutes, 119 wh/km - apx. 191 wh/mile). To summarize - Using the heater - 220 wh/Km (354 wh/mile) - Not using the heater 119 wh/Km (191 wh/mile) Granted, this was an extremely off the cuff test, and while I tried to maintain a similar driving style, I was probably 10 minutes earlier than usual, (which for the GTA can make a significant traffic difference). Even accounting for a bunch of those variables, I have never seen a wh/Km figure anywhere near that in the month and a half I have had the car. I know there are lots of posts pointing out how much energy the heating system takes, but I was personally very surprised to see the difference. FYI only.