Hmmmm, I agree w/M5James on the thermostat test at home (watch out for those fan blades!).

I recall that there was a way to get the OBC to go into test mode and read out actual temps (in deg C, of course) so you could see what is going on. I know you can do it on my 2002 M3, not sure about the X5. Was it on the tips/tricks thread?

You don't want your engine running below optimum temp all the time. Not fuel efficient is one reason.

If you turn the heater on, how long does it take to get warm air out of it?

My gut tells me thermostat not closing all the way or the fan clutch is locked up (or both).

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Kirk
Las Vegas
2016 X5 40e Mineral White/Black Dakota Leather, ZLL, ZCW, ZDA, ZDB, ZPP, multi contour seats, rear side window shades, HK stereo
2011 E90M3, 6-speed manual