the butt dyno says yes they do.
Since i installed them i hadnt seen a major uptick in the mix commuting mileage (LA FREEWAY/SURFACE STREETS daily of about 50 miles) but looking at the sheet, it looks like i dip less into the high 17s low 18 mpgs as much since installing and have more 21/20 mpg tanks.
note i also rebuilt the front end two weeks after installing the uels, bearings, bushings, tierods, cv's at the same time so not a solid baseline.
plus the center 1:1 rear idler gears bearing exploded back at the start of june and i havent had time to source a new transmission/center diff set to replace it so there isnt a ton of data.