Congrats only 84000 miles to go to beat my M3 convertible I sold to a friend a few months ago. Running perfect OCI per BMW up until I pulled the head to check valves and top end. Waste of time didn't need anything but put new valves and springs in.
Key to getting to this mileage is long drives at freeway speeds. Also it helps if you live in a climate that is mild which the OPs isn't.
BMWs last a long time if cared for and driven enought to completely warm everything up. In fact virtually any car will last a long time doing that.
Nice tribute to OP. I too don't sell my cars until they have significant years >12 or miles >200K and sold mine for slightly less than the going rate and had multiple buyers. Sold it to a friend in case he has any issues I can help him out.