I'm kinda curious also. From lurking around a bit it seems that the 5.4 does about 1-1.5 better than the V-10. The V-10 seems to average about 14+/- overall with a light foot, and decreasing quickly depending on the weight of your foot. None of this info is first hand though, I have been a long time lurker and remember these #'s from different posts over time. Shortly I'm going to be buying a 250 4x4 SC SB with a 6spd, and I'm curious how much the extra weight of the 3/4 over a 1/2 ton affects the 5.4. None of the dealers around me have any 5.4 super duties for me to test drive, I'm gonna have to order my 5.4 F250 /ubbthreads/images/graemlins/frown.gif Although the V-10 will only cost me $450 more and 1-1.5mpg, so it is kinda tempting. I just can't justify the cost of a diesel that is 4k more, and at a time when diesel in my area cost a few cents more that premium /ubbthreads/images/graemlins/confused.gif