It really depends on your driving mix.
We had a 2003 325i SULEV with steptronic. It got about 13 mpg in 100% city driving. Pure freeway driving, it would get mid-high 20's.
On our X3 3.0 with steptronic, it gets about 11 mpg in 100% city driving. Don't have a pure freeway number yet, but on some short trips with the OBC reset, it appears to be mid 20's.