Not sure about the LMM, but my LBZ with the Quad on 90hp......no lie....averaged a hand calculated 26 mpg from eastern NC, to Tennessee back before Christmas. I tracked the miles via GPS and the odometer (which are now identical) divided by the gallons put in and came up with 25.8 mpg at an average speed of about 70 mph. Had my wife look at the GPS and calculate it herself to double check me and she got the same thing. Filled up right as we were leaving, then didn't have to stop for a while. Went 452 miles before I decided to stop and fill up and only put 17.5 gallons in the tank. My fuel needle gets down close to the E mark when I've only burned about 18-19 gallons and at that point I usually fill up just so I don't have to worry about it. I know the tank is 26 gallons, but I've never had to put more than 21 gallons in it.
I thought it was wrong to start with, but I re-checked it on the way home (filled up as I was leaving TN) and went 430 miles before the wife had to use the bathroom....and filled up again there while I was at the station. Had driven 430 miles, and only put 17 gals in this time too which came out to just over 25 mpg. Again at an average speed of about 70 mph.
Now I wasn't towing anything and cruise control didn't come off the whole time. Not sure if 90 hp is the best fuel economy tune but it sure has netted some good MPG's for my truck.