My 4.0/AW4 4x4, running 235/75R15 I get about 16 around town, 19 at 75mph, 21 at 70mph, 24 at 65mph, all running 87 octane. Mileage has been corrected for tire size.
I was afraid the 4.5" lift was going to affect highway mileage, but it seemed to have had no effect.