General  - 
We were out of town for a couple of days and I thought it would be interesting to see how the Model S behaves during that time.  It was parked in a garage that's heated to about 40F.  While we were away, the outdoor temperature was fairly cold so the average garage temperature was probably just about 40F (with a few windy cold spells and a few days above freezing).

Recharging usually occurred after about 30 hours, but one time it recharged after just 24 hours.

On average, the car lost about 7.5 miles/day of charge, presumably mainly due to heating the battery.

Upon our return, the car had a charge left of 229 miles, just slightly below the 235 miles of charge that it had when we left.

The car had firmware v4.1 installed.

It'll be interesting to see how much of this behavior will be tweakable in the future.  It'd obviously have been nice to say that we won't need the car until our return and hence the car shouldn't bother with heating the battery more than absolutely necessary.

For anyone curious, the raw data is available in this spreadsheet:
David Mosberger's profile photoJohn A. Tamplin's profile photo
So if it was plugged in and used line power to heat the battery (which I presume from your graph), then why does it use up any range at all?
The battery is used to heat the battery.  Every so often, the battery is replenished.  I checked the remaining range upon returning, which happened to be 41 hours after the last recharge.  So between the last recharge and my checking, heating the battery had consumed the equivalent of about 6 miles.

BTW: I had missed one recharge in the spreadsheet calculations.  With that fixed, average loss (or recharge/day) is 8.35 miles.
Not that I know of.  I do expect such things to be available with the smartphone app, whenever that comes out, however.
I'm surprised it draws from the battery at all when it is plugged in -- for the LEAF, if it is plugged in it draws only from the line to run HVAC and the battery heater, though it can't do much to heat the cabin if it is actually charging the battery, so you can set which one gets priority.
+John A. Tamplin It makes sense to me: the car obviously needs to be able to condition battery temperature when on battery power only.  Given that, why add a bypass path to the power plug?  It'd only add complexity.  Add to that that the Model S plug has to handle 120Vac, 240Vac, and 480Vdc.  Seems to me that would add a fair amount of complexity for little to no gain.
Well, I will be disappointed if there is ultimately no way to run climate control off of line power -- I already miss that feature from my LEAF, having it warm up while on line power and not have to be cold while it burns up battery power heating the cabin.  If you are going to have that capability, I don't think being able to run the battery heater off of line power adds much complexity.

Regarding voltage conversion, you have to convert it to the battery voltage (or a bit above) anyway so again I don't think anything is added.
+John A. Tamplin Don't know.  It'll be easy enough to find out once cabin-preconditioning support has been added.  We'll either see a constant power draw or periodic re-charging (would the AC be off during re-charging?).
+David Mosberger At least on the LEAF, you can specify the priority between charging and running HVAC, and if you choose HVAC you may not get much charging depending on how much heating/cooling is required.
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