Oddly enough, I'm having the exact same problem on my 2004 3.0 X5. Temp guage shoots up to max indication within a few minutes of starting. Shut off... restart... temp gauge sits about 1/8" off lowest indication and stays there. Heat had been ok when this first happened a week ago. Now tonight... barely any heat... if any at all.

Normally, the engine temp gauge sits about at the midway point.

Will be bringing it to the dealer on Monday.

Thanks for the info and glad you got it fixed Freddy.