My roomie picked up a trickle charger on her way home from work the other day. Yesterday I hooked it up to the Bimmer's electrics, let it charge, then fired the car up and tooled around the neighborhood for a bit.
Today when I got in the car to run to the store, I went to turn on the radio. The factory head unit's display lit up with "CODE: _ _ _ _ _". For the first time in the eight years I've owned it, HAL the Brainiac Car Radio had been deprived of current, and therefore thought it had been removed from the car.
I'd forgotten that those Teutonic gnomes have installed a security feature in their radios that makes them useless if boosted, unless you have the correct code. And guess what?
That's right: I flipped through the owner's manual, warranty booklet, keyless entry/antitheft manual, and every other scrap of paper associated with the car, and no code anywhere. How festive. I guess I'll call the nearest BMW dealership on Monday; I'll just seethe a bit until then.