Just as a side note.. last year I had the AC compressor replaced on my M62tu V8. The one I supplied was broken so I ran the X5 for two weeks before the garage could get round to installing the new one.
During that time I noticed a marked difference on the temp gauge in that the needle was always between 1/4 and 1/2 whereas before it was always stuck at 1/2 .
The engine also ran smoother and quieter.
I too have been searching for a way to run my engine slightly cooler. I put in Redline Water Wetter the other week but I haven’t noticed any difference other than it gets up to temp faster.
I may get a lower temp thermostat but saying that, I had the car in for a check a few years ago and chatting to the technician he said that mine did not use map cooling. There is an electrical connection to the thermostat housing though so I think he got that wrong..