I took the X5 out yesterday afternoon for a drive and ended up putting almost 80 miles on it. It is so smooth and quiet. I'm happy to report that after replacing the thermostats, operating temperature and behavior is practically identical and I haven't noticed a magical difference or faster warmups. It's warmer out than the dead of winter a few months ago when I was looking closely, but 80C is reached about a mile sooner (ambient ~20C compared to ~-15C). It plateaus around 87C instead of 83C or was it mid 80s? Anyway, the point is even with a new coolant thermostat, it doesn't automatically run at 89C even in warm weather, and is largely dependent on engine load. This is the same behavior I've noticed for over ten years and 140k miles. It's normal.

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8/2011 X5 xDrive35d Sport, Black Sapphire Metallic, Black Nevada Leather, Fine Burr Walnut Trim
2/2001 M5, Jet Black, Exclusive Complete Black Walk Nappa Point Heritage Leather, Black Cubic Trim