A quick look on fuelly shows that the 2.7 turbo appears to be the best as far as fuel economy is concerned. I thought I looked before and saw the non turbo 3.5 got better real world mileage. The mpg number that the largest number of people were getting with the 2.7 is 19. With the 3.5 non turbo it was 17. If I was getting one of these things I really would have a hard time picking between the 2.7 and the non turbo 3.5.
But ford makes my decision easy, no manuals offered. And anyways, the only pickup truck I would drive is one of these:
