we're getting about 26.1 MPG with 20/80% city/freeway on our S-drive. We've got about 1500 miles. It's been increasing slightly.
For me, I don't think it will get to the claimed 28 MPG. In most of our other cars used in similar driving patterns, we've been able to get hit the EPA combined ratings exactly. That's not to say we are get the claimed efficiency in any car because we drive mostly freeway and over speed limits 75-80 MPH cruise. I think the X1 is not fairing as well because turbo engines are as efficient for our (and maybe everyone's) driving style. I've had one other Turbo and it also seemed a little harder to hit the combine EPA rating. So if one were to drive the sDrive conservatively, maybe, but it wont be easy.
Eco Pro seems like BS to me though. It's nothing more than a restraint system for those who don't have good throttle control and/or self control. It dulls the throttle response and it can be annoying when it finally unleashes the restraint and downshifts unnecessarily.
I can only see it being useful on a long hwy cruise where the HVAC cycling may be convenient to manually turning the AC On and Off. Someone ought to challenge the benefit of the mode by seeing if any miles can be gained (in Eco Pro) with cruise control On and the HVAC Off. I'll certainly try for a 5 min increment the next time I get chance on a long flat freeway.