Thanks for the timing chain information.
Here's the two cars I'm considering. The price difference is actually around $2400, although I'm now realizing that the 2016 is not CPO.
2016:
https://www.bmwoffreehold.com/used/B...fd7c1d6fc1.htm
2015:
https://www.flemingtonbmw.com/used-F...3B5C52FF960970
There are a few other 2015s in this range/mileage available at other local dealerships.