Interesting. I have both the 3.0si(2007) and the older 4.8is (2005). I love the 4.8 for the power and sporty drive. It's def. a head turner. The only thing I hate about it is the fuel consumption. It's brutal! And , it's a rough ride if you live in areas where streets are not nice and flat. It's pretty much in all ways a sports "car"....

The 3.0is is pretty much all the opposite. It's smooth , refined and with the "si" model you get something like 50hp more than the regular i6 (3.0i). So it doesn't lack power. Of course it can;t be compared to the 4.8 power-wise but it still has some kick to it.

Also , the noise level in my 4.8 is higher and the price of those freak-en staggered tires is scary(you can always go squared though). But bottom line , the 4.8 has that exiting and fun factor to drive VS the relaxing and smooth factor for the 3.0si....

Good luck and report back with your choice ;-)

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His : 2005 X5 4.8is (SOLD)
Hers: 2007 X5 3.0si (SOLD)
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Retired:
1999 518
2000 323i
2002 M3 (beautiful car)
2003 330Ci