I know is a late reply I didn't have much time to check my messages lately, but yes my 328xi is auto. BTW same thing happened to me in the winter on the second tank 14mpg I told the dealer that he sold me a hummer

. Some guys sugested to take the car on longer highway trips and then I got about 26mpg (highway only). Right now on strictly highway it does 26-28mpg however city (NJ no highways 5 miles comute) it still does about ~15mpg. I took it to the dealer and have been told that there's nothing wrong with the car and that what I get is about average for central NJ (JKM dealership).