I driven & owned many Ford cars & trucks with 4.6L & 5.4L V8's. I've never seen a 4.6L in a van or truck get any better gas mileage than a 5.4L when loaded (few people, gear, etc.). My dad had a 2wd F150 SCab with a 2V 4.6L and he got worse gas mileage than I did with my 4wd F150 SCrew with a...