Just picked up an 09 328i X-drive AT. I only have three tanks worth of gas in the car, but so far, I appear to be doing about 28 MPG combined per tank. That's at about 85% highway.
I was curious just how much I could squeeze out of the engine. So on a lonely stretch of highway, I set the cruise to 59 MPH and let it go a little over 50 miles. The computer was reading 34.5 MPG just before exiting.