I have had X3 05 and now have X5
X3 is more of an ofroad touring, while X5 is luxsury SUV
Sitting space is better on X5, while storage is better on X3
Overall quality impression is better on X5, howeever the reality is that X3 wil couse you less hours spent here or in the shop

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X5 4,4i-06 Current
330Ci Cab-03 2007-2008
MB E55 AMG-03 2006-2007
Z3 2,8 Roadster-98 2006-2007
X3 2,0d-05 2005-2006
320d-99 1999-2005