Originally Posted by 02kingranch
I have 5.4 and 35s and only get 9 after hand calculating. I am super easy on the gas but have 0 performance mods and only 3.55s which is my downfall
Have you flashed your ECU to account for the change in tire size? If I used the odometer to calculate before I adjusted for tire size, it would figure to about 9 mpg. In 240 miles (about a tank) my odometer was off about 40 miles. In other words, my GPS read 240 and my odometer was at 200.