There is a $600 upcharge for the 3.5 and vs 5.0 4x4 mpg on the highway the difference is 2 mpg( 22-24). The only real difference noted on fuel economy is city driving, of which I do almost zero. Given the miles I drive at current fuel costs it will take 7-8 years just to make up the $600. As for maintenance, per the mechanics I have spoken with, there are 2 issues that I want to stay away from the possibility of....cost of a turbo going out and the additional labor cost of having to remove and replace turbo for many unrelated issues. These are BIG costs that there is no chance of with a 5.0.