Interesting.
I have a stock 2006 full time 4wd V8 getting 17.7 city. I was getting 17.8 but then I put on new tires and lost .1 mpg lol
No lift, tire size is 265/65/17
A/T Coopers. And I feel like I have a heavy foot at times but not on purpose, and then sometimes it's good to see if "she's still got it" lol
Only "modification" I did was change the air intake filter to a K&N. Just the filter. The whole assembly is illegal here in California.
So no I don't feel as if though that's normal. I do remember when I purchased the truck it was showing 14.8. And it didn't change despite my driving abilities and after a couple fill ups I decided to reset it at the gas station. Filled up and headed on freeway, got up to 24mpg, then got off freeway and drove city, it dropped to 17.8, then with new tires down to 17.7, and now it just stays at 17.7. Hope this helps.
06 T4R SE V8 4WD SM