Depends on how it's used.
Stock application, stock tires, proper tune, it can easily obtain 25mpg or better.
opening up the exhaust by adding a header and 2.250" exhaust will net more power and better mileage.
Add 33" tires with stock gears on a 4x4 and you'll get about 19 mpg depending on how you drive it.
I have had both and experimented with both, in my experiance, the EFI got better mileage than my carb truck did. best I ever got out of the my '87 carbed 22R was about 23 mpg, while my 85 Runner on 31's would get about 25 on the highway, 27 once I opened up the exhaust, but dropped to 20 when I put the 33's on it ( go figure)
Then I messed with the AFM and the power went up a bit, but the mileage went to about 19 on the highway.
the 90 Runner I had ( 4dr on 31's w/22RE ) got best of 22mpg on the highway