19/26, are you going downhill with a backwind?
I hit 20.5 in my 99'4runner, 19.5 in my 89... i dont see how 26 can be done. I dont even think it's possible on a 4x4. the s-runner's (2wd, 3.4 5speed 2wd tacoma's) only get 25mpg, and they weigh 800lbs less and have way better aerodynamics.
Oh, and x-runners get 15-21mpg, anyone that says they get more, is BS'ing.
Sorry, i dont believe these claims, unless you have a 3rz...
BTW, throttle body spacers dont do anything, it's all a placebo.

89 4Runner
3" BL, M/T locks, 33"bfg mt, bilstein, Kayline, tubebumper, toyotafiberglass panels
TBI: Elocker,3.4 w/ORS,b+b,S2Sstg2cams,arias pistons,P+P intake,TRDs/c,URDpullies+7th,downey headers,MAPECU2,WEGO WB, SupraMAF,walboro255,stg4clutch, EPaOo2 sim