I have just tested some of these on my (UK) '04 car (with nav) and can confirm the following:-

The cigarette lighter socket stays live even after several hours. A post here indicated that the car goes into a deeper 'sleep' mode after an hour and power to this is cut, but on mine it definitely stays on. Is it possible to change this so it DOES go off?

You cannot turn the radio on without turning the key to at least position 1.

Both of which are a shame as they'd be useful. Please enlighten me if I'm wrong.