1978bmx 
2008 BMW X3 SUV 3.0si 4dr SUV AWD (3.0L 6cyl 6M)
N52 engine really has problems
 I purchased my x3 new, did my research and the x3 came in to be up there with the 3 series in quality.  At around 60k the valves started to tap like crazy, (metal on metal sounds- if yours is doing this it is not normal! It needs to be repaired- don't let the dealer service people tell you it's air bubbles in the oil. It will lead to premature engine failure this should be covered under warranty) the tapping sound was especially loud with cold starts. The engine cylinder head was replaced, but the sound is more of a thumping slamming sound now, it will be in the shop this week again! Even the BMW techs I've talked to, feel the quality of BMW is really slipping. 