I have a 2011 XC with naybe 2,000 miles. Very slighlyt modded exhausts, and the HP air cleaner. One of the things I noticed immediately was the combination of a low fuel light coming on too soon, coupled with rather poor mileage, 32-36 or so. I added a Power Cammander with auto tune (I plan to get Lloydz cams) and although it seemed to run a little better the mileage stayed the same.
My buddy Marc has a 2011 Vision, and he was getting about the same mileage (identical set up as mine).
The issue for me was range on a tank. I want over 200 miles. After I whined enough, Marc contacted Jamie at Fuel Moto (where we purchased the PCs) and asked if he could supply us with different maps. Jamie did (for free) and leaned out the AF ratios at lower throttle and lower RPMs. The auto tune then adjusts to these settings.
I have run two tanks of gas thru it, one in the mountains at 43mpg, and another on the freeway at 80, with some headwind for part of it, at 36 mpg. So far, about 5-6 mpg increase
Marc has noticed the same increase.
I realize some of you are getting better mileage than this, while others seem to get much worse. Just fyi for those of you who might want better mileage. particularly if you have a PC..