Thanks for the great write-up. It made my experience today close to bearable. Forgot that I left the car outside last night and went to drive it this morning to run a few errands. It is -20 Celsius out - that's the equivalent of -4 Fahrenheit. Dead battery. I shouldn't be surprised as I'd seen a few low battery warnings lately on the dash.
I ended up buying an Energizer 94R battery from Wal-Mart for $117. For the 2006 330i all of the application guides are wrong and recommend a 48 but it's physically smaller than a 94R. The replacement was exactly the same size as the OEM battery with the vent location in the same spot.
Now I've got to decide whether it's worth heading to the dealer during the week to re-program the car. Stupidest requirement ever.
I'm now trying to get my core temp back up. My feet are freezing!!!