I've been a member since I purchased my 545 in February but never logged in. I moved up from an 06 325 and love the change. The change in power is great also.
I was reading a topic on battery problems and I am experiencing a simular problem. After driving the car two days earlier, I found the car completely dead.
I had to have roadside assistance to get the car started. Took it in for service and they couldn't find anything drawing down the
battery. Is this a common problem with the 545 series?

 

Not common, but a battery is a battery. Only a few things could be wrong. Check alternator.

P.S. - Welcome =-p

 

What year car? In addition to what Howitzer said, it could be that a module isn't allowing the car to enter sleep mode.

In an early version of the car's software, I seem to remember a bug where something as simple as a cell phone plugged into the lighter socket would case a battery drain...