[aerohead]

A decade or so ago, I read an online article ( Ford Motor Company engineers ) which stated that new car engines were already broke in, and if any 'break-in' was mentioned by the manufacturer, it would actually have to do with the ring-and-pinion gears in the differential. It revolved around some issue with micro-polishing of the mating surfaces.
Computer-Aided-Machining and robotics are so good today that, manufacturers hardly inspect more than a couple of engines randomly, out of thousands assembled daily.