Don't worry, your Tesla S works in winter.
 

The batteries and your tush should be warmed up after your morning shower, the traction system will keep it in your lane and your door handles free of ice.

http://www.youtube.com/watch?v=GS9uDJGi52A

...but physics still say cold temps will lower the discharge capacity of our lithium batteries; electrolyte conductivity loss.

How to Prolong Lithium-based Batteries - Battery University

I wish I could preheat my car to preheat itself off the grid.

AntiochOG -
Just mod it so you can! ;)

Agreed.

Space heater + remote switch (for Christmas lights) = warm car anytime

Hit the button 20 minutes before you go and you walk out to a warm car. I did this for a while on my Paseo.