I had the X5 taken to an Indy shop, they said bad timing chain (based on low compression, they didn’t pull valve cover) and quoted $4500 labor to R&R engine plus cost of replacement. I trailered the car home so I can properly work on it. Removed the valve cover and installed the camshaft timing tool to find that everything is perfectly aligned! The VANOS bolts are intact, timing chain is tight and guides are in good shape.
More mystery. Now looking at blown head gasket, but there are no detectable symptoms other than the low compression.