Go for the '08, skip the sport package, stay with the standard wheels. The X3 rides a little firmer, and IMO is sporty enough with standard suspension and tires. The '07 and '08 have very few changes between the two years.

Lots of power with the '08. We just took delivery of our '07 a few months back. We chose the X3 3.0si over the X3 3.0i; in the US you don't get both options, you just have the si.

Incidentally, we traded a 325xi (sedan), but it was an E46. My wife likes her new ride, particularly the PDC.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue