What AC linked is probably the best option.
But also be careful of a few things.
1. Remote starter or starting and long idle is not really the best things for these cars. Better to start and then drive.
I did see that thread but since it was a single sku I wasnt sure and more digging for options. Thanks thoughSee this thread on a BMW block heater. As I recall there was a BMW dealer in BC that was selling them ... may be in the linked thread.