You will not be disappointed with the 550i Sport Package. You must order the sport package with the sport transmission which includes the "wow" button and paddle shifters. You also must order the Logic 7 audio with the USB iPod adapter. Finally Heads up display should be on your option list along with NAV. This car is very comfortable at 90 miles per hour on the interstate. At a steady 75 MPH you will get 24-25 MPG, about 17 MPG around town. I have owned a 2006 750LI, a 2004 Porsche C4S Cabriolet, a 2003 540i Sport Package and other than the open air motoring of the Cab this car takes the best pieces of each and puts them in a single package. Find a good used one with low miles!
One of the best bluetooth integrations I have seen. The car looks like an M5 without the torture in cost and insurance premiums. A true sport sedan that can carry three or four golf bags while your passengers enjoy 7 series like comfort.
The 2011 550i has added the twin turbo V8 along with some pricey 7 series options. When the full sport package is out the 2008-10 550i will finally have a competitor in this class. An X- Drive version may be nice for the Snowbelt but running snows on 18 inch wheels is just fine for us up north.