What engine?

Here is a link you can check all three choices.

http://www.fueleconomy.gov/feg/calculatorSelectEngine.jsp?year=2006&make=Jeep&model=Liberty/Cherokee%204WD

Best of luck

all depends on engine, My jeep liberty has a V6 3.7 liter and i get 17 miles to the gallon

I have the 3.7 L V6, it is not as good as my Explorer, i get 15-16 in town and only 20-21 on the highway, if I'm lucky.  It is a heavy vehicle, which, I can see some safety, but, my explorer had a 4.0 L V-6 and i would get 17-18 in town and as much as 24-25 on the highway.

i don't know my engine size and such.. but i do know that i get great highway millage and i drive 120 miles just one way to get to school. and one way i only use around a quarter of a tank

Not the best, but pretty good.  I would say average.
Not as good as a car, but certainly better than a full-size pickup.

I have the 3.7 L with 4x4 and a K and N air filter and I have been getting about 19 in city.