I have the FX4 (all stock w/o eco mode) with the falken wildpeaks as well and regularly get over 30mpg's during my 75mph cruise to work/home daily, and sometimes close the 500 mile tanks when traveling the 55mph highways. i have almost 25k miles and use the cruise most everywhere and approx. 80% highway driving normally.I've yet to get more than about 27-28MPG out of my 4k FX4 with the wildpeak offroad tires.
I suspect if I had some more 'eco' focused rubber I might be able to creep into the 30s.
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