Looking to buy used Grand Cherokee

Hey all, I am looking at buying a used Grand Cherokee 05-08 with <50K miles. Is there anything to look for/avoid, any model year better or worse? Also which motor is the best, is the V6 big enough & reliable? Looking for a good mix of power & mpg.

Thanks in advance.
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I have always subscribed to the tenet/philosophy that when side by side, same speed, etc.etc.etc.,
8 cylinders do less work pulling than 6 cylinders do! Therefore an 8 should last longer than a 6? It makes sense in theory but I can't actually prove it. The design of either the 6 or 8 engine may also be a factor. For what it's worth!

i average 20mpg with my 04 4x4 i6 grand but i drive on average 45- 60 with very little stops in my commute but i do know that my grand only weighs 4200 with a full bag of gas and me in it. i know for a fact that the 05's are over 5. gas mileage be damned. also i know for a fact that the i6 will easily go 200k with oil changes and maybe a crank position sensor or two.

Does anyone know about the reliability of the new V6 vs. the smaller V8 (not the Hemi)? I am leaning more toward the V6 as long as it is strong enough for the vehicle and reliable.
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