Instead of a conventional rear-view camera, Cadillac has come up with one that offers either the standard reflection or the view from a camera on its 2016 Cadillac CT6
sedan and 2017 Cadillac XT5
If the driver chooses it, the rear-camera view can be on full time as you drive, projected on the rearview mirror. It's convenient for when visibility is compromised by a backseat full of passengers.
USA Today article here