I used to own 2008 X5 3.0i and now I have 2012 X5 5.0i
there is simply no comparison - 5.0i actually allows you to enjoy BMW's drivability while 3.0i feels like a truck
I'd say that 5.0i is an excellent vehicle, however if you can't afford it I'd go with Mercedes ML350 instead of BMW X5 3.5i as you'd get more comfort this way while getting similar performance
Good news is that the residual on 5.0i model is (or at least used to be in November 2012) 5 percentage points lower on 36 month lease than 3.5i, making 5.0i somewhat affordable
