Re. the clock idea. As far as I'm aware the unit has no means of keeping time while it's powered off. Setting it manually each time is obviously not practical, but it could maybe get the time from RDS (Radio Data System, digital data on a subcarrier of FM broadcast radio) at least in countries that have RDS such as the UK which should allow it to get the correct (or at least the current FM station's idea of correct) time within not many seconds of booting up.

My Philips Carin 440 head unit has 3 clock options; user settable, from RDS, from GPS.

Cheers,

Mark.