2008 LMM cc/sb 4whl 3.73 all stock 11 hour drive home from purchase I checked DIC speed vs mpg.
75 low 17
65 18.5
55 19.5
hand calculated 75% city 25% highway 16.5 mpg. I drive it easy, I keep it under 2k 95% of the time. Only the occasional romp.
Removed exhaust, put on diamond eye d/p, 5inch mbrp straight exhaust and Quadzilla S2 Econo tune.
Maybe just over 1mpg improvement from stock, says the DIC. I say as B/A as it sounds I at least gained 5mpg hahaha!! However I don't get the 10-12mpg during regen anymore....
Now put on 20 x 9 kmc monsters, 33 in terra grapplers, crank the bars some and have lost almost 2mpg doing so. Don't know if lifting the front had anything to do with it but I am sure adding wheels & tires that weigh probably over double what I took off had quite a bit to do with it. Hoping to get some back with EFI when I get it.
Of course I did not buy the truck for mpg but this thing gets about the same as my 1/2 ton silverado 2wd did unloaded while much better mileage pulling my trailer.