I love the V8 X5s for what they produce and the power they have. Between V8 engines i would say that the the N62 is more expensive to maintain particularly from the perspective of the valve stem guides. That repair job is a $3-$4k job. The timing guides on the M62 is the biggest point but many have been able to do it as DIY and there are lots of procedures out there to help with this one. The M62 also have the vanos rattle tractor sound but a seal repair on these is pretty simple and highly documented as far as the procedures for the DIYer. I like the 2001-2003 4.4L but the 2004-2006 V8s are nice once you have the valve stem repair completed. I 4.6is just because it was that slightly different M62 motor with more power and I love it.