When I park my car in the underground car parking very weird thing happens.
When I returned to my car for example 5 hours later I find my clock display stuck at the time of parking. And when I reach to open air the display becomes normal and real time clock is displayed correctly. Something related with GPS I think but why?
I guess that you don't have internet-coverage at the spot where you park your car. The clock/time is set automatically from time-servers on the internet.