well, I got a real good deal on a Grand Cherokee... with a v8. Mileage wise, the I6 4.0L and V8 4.7L are really just about the same. 15/20 for the I6, 14/20 cty/hwy for the V8. That ole 4.0L is a bulletproof motor (my current XJ has 400,000 on the clock) but not terribly efficient. I did the math and if I did strictly city driving, it's a difference of roughly $5 every 1000kms. It'll take a lot of miles before the extra fuel cost adds up to what I've seen other vehicles cost.
And yes, it's a Jeep thing. I looked at other vehicles but in the end, the heeps have everything I am looking for.