After 3 months of perfection, my 4S had a dead 12V battery. Dealership had it 1 week, said is was not the 12V issue, but a problem with the charger which was reprogrammed and given a new cable. My issue is, was it really necessary to drive the car 20 miles to detect a problem with the charger? I can understand a couple of miles but not 20. Before I formally complain or just blow it off I wanted some input. Service manager said Porsche told them to drive the battery down and recharge it, but it seems like their computers should detect issues by running diagnostics.