Changing the FOB batteries appears to have fixed problems I was increasingly having with starting my car. The moral of this story is; don't hang your keys < 20 feet from where your 10 Series is parked.
It took me a while to find some instructions on how to crack our FOBs open. It turns out that the FOBs, like our tires, come from the Prius. Googling FOB+FRS will get you squat. Here are some good instructions with plenty of pictures:
http://www.paulstravelpictures.com/T...acement-Guide/