So I've been driving a Roadster for about a year and we bought my wife a used Model S about a month ago. The local Tesla Service center was really great in providing me with some general information about the service history of the car prior to purchasing it. I bought it from an owner in Seattle. The car was also in about 2 weeks ago for titanium under shield and rear cup holder installation. My wife got a call from Tesla this AM and said they got a notification that the 12V battery needs to be replaced and that they wanted to send a Ranger down to replace it under warranty. They explained there is an algorithm that determines when the battery needs replaced and they don't know about it until getting the notification, which they got this morning. That's pretty awesome service! They know the car is going to fail before it actually does! I had no idea they could monitor the 12V battery like that remotely, the longevity of which is an issue in the desert heat for many cars. I'm a little surprised it needs replacement a little over a year and having come from Seattle, but I'm ecstatic Tesla service was on top if it and is taking care of it for us. Amazing.