Maintenance-intensive — go in eyes open

These are expensive flagships to keep. The recurring items are air suspension (struts/compressor), DI carbon cleaning (every ~30-50k, ~$1,600 at a dealer), failure-prone intake-manifold flaps, fuel pumps (~80-95k), the oil-filter-housing O-ring (hardens ~40k, needs intake removal), and O2 sensors (some need engine-out access). …