Apparently, the new 2012 328i with the turbo-4 is EPA-rated at 24/36 mpg (US) with the 8-speed auto. That is really quite good if people can achieve close to it in real-world driving.
The 335i manages 23/33 mpg with the auto.
http://blog.caranddriver.com/2012-bm...6-mpg-highway/
You have to figure the xDrive version will achieve 30+ hwy, which will make it one of the more efficient AWD vehicles that has a soul.