For the longest time I just used low on my 2012 Outlander 1000xt for everything, and when going back to our annual camp site (40 miles),I would be lucky to have 1 bar on the fuel gauge, and when towing a trailer back there I would have to put fuel in before getting to the camp site to make sure I didn't run out at an inopportune time. Then one day had to make a high-speed run out of there, put it in high most of the way out and when I got to roadhouse, I still have 3-4 bars left. (thought that I could go all the way back in without refueling, but of course I didn't try that). Anyway, after that, I started using High gear whenever I could (anytime I thought I could be running above 18mph). I did not keep exact records, but my guess would be that I gained at least 2-3 mpg by running it in high and probably more.