FWIW, I had my car parked for 18-days, and when I returned and started it up after a vacation, it announced it had gone into hibernation mode and shut down various things that normally would have continued to run (I'm assuming to save the battery). As a precaution, I put my trickle charger on it when I got home, but I never saw any other effect. The steering wheel did not go back to its programmed position and it forgot all of my programmed radio stations, but has returned to working normally since. I'm assuming from this that it does not save that stuff in NVM, but in volatile memory, and that was shut down to save power (along with probably other things as well).
Last edited by jadnashuanh; 11-12-2012 at 12:34 PM.