I have just ordered a black 65th anniversary V6 JC 4x4. Gas mileage is a small concern for me. I live in Southern California. I currently have a 97 grand Cherokee 4x4. I only use the 4x4 when I am in the Mts. or on the beach. My concern is how does the 4x4 system work in the JC? Can anyone explain it to me? I put the Cherokee into 4 wheel drive. I get 16.1 miles on average in the Cherokee. Will the way the 4x4 sytem in JC is set up use a lot more gas, or does it only start when you need it? Thanks for your help on clearing this up for me.