i have a 5.8L in my truck but other than that it's a lot different, but i still only get 11-12MPG and that is on nice days when there is no show on the road, in bad conditions i get about 8-9MPG if im lucky haha... its a '96 F-150 5.8L E4OD A/T 4x4 w/3.08 open diffs and 265/75R15's which are only around 29 or 30ins. ....