I have a 2007 mega cab 4x4 1500 with the hemi. I also have Superchips tuner, K&N CAI, and Gibson cat back exhaust. I run 93 octane because of the tuner. I get 12.5-13.5mpg. That's a mix of highway and city driving. Probably about 60% highway and 40% city. Lately it's been getting in the 13's, but I just rolled 10000 miles so it's probably the best I'm going to get. Hope this helps you.