I had some issues with settings being lost when I wanted to open/start the car. Apperantly, the car has an intelligent power management system, and in case of a poor battery, it first shuts down not-needed things like welcome light, looses time and date settings, looses radio presets and so on. Then I once saw the low battery sign when I stopped the car.

Dealer replaced it and no issues since. There are so many electronics in these cars, that the batteries are coming way to short. They are still using the same batteries (power wise) compared to 10 years ago, so they almost 'must' fail pretty soon.