My X5 3.0i 2001 has a problem related with cold weather either.

When the out air is below than 37?(not sure) coolant temperature
goes to the end of the gauge after I drive 10~12 min. And heat
dosen't getting warm soon. After the engine restart the gauge turns
normal but still cold inside.

This is different from temp' problem,

There was a flat battery problem yesterday. It is second time and I
think something wrong with electric part of my X5. Mechanic brought
potable battery and started engine after 24 hours flated battery.
It looked like everything OK before I found the language changed
Deutsch. And there is nothing on odometer. I can't change language in setting menu.