Having had a RX350, the X5 is better in every way except for gas mileage (4.8i). I have rattles but also had rattles in my RX.

When my lease is up at the end of the year, I'm also considering the diesel as a replacement.

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2012 F10 550xi Carbon black/oyster
2011 E92 M3 SSII/black
2012 W166 ML63 Steel grey/porcelain
2007 E93 monaco blue/beige (retired)
2010 E70 35d Space grey/saddle brown (retired)