Love our 35d. When test driving, I wasn't sure about the noise but after 6 months of ownership, I actually like it. The X5 is the wifes (my dd is the M3) but I drive it quite a bit and don't notice any 'smoothness' issues - but I don't drive the X5 like I do the M3...

We bought slightly used which dropped the price (with the options we were looking for) into our price range.

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'06 M3 Silver/Gray
'11 X5 35d Sparkling Bronze/Oyster
'88 M3 Silver/Black, 47k Miles, Stock, Garage Queen...