I have 6,000 miles on my 135i and my total average is 25 mpg. Driving is always split 60% highway/40% city driving.
Pure highway, I can get up to 30 mpg if I nurse it w/cruise control set at 75 mph. City mileage ranges from 20 mpg (with a light foot) down to 17 mpg (with a lead foot).
All things considered, my WORST mileage is bang-on the EPA city estimate, whereas my average mileage is EPA's highway estimate. And my real-world highway estimate is 20% better than that!
Hells yeah