I went from 6.6 Duramax to 6.4 Hemi and my MPG with summer fuel are nearly identical for my daily driving mix. The winter fuel knocks me down 1-2 mpg with the gas. Some of the reports of mileage probably have a bit more hwy than I do. I'm close to 50/50 and get 14-15ish with summer fuel. On a long flat hwy if I keep it at 55 (nearly impossible :)) I can see upper teens or even 20. Stop and go driving and sitting in traffic REALLY kill the mpgs with this truck... much more so than with my diesel from what I can tell.
My towing mpg are as reported by others. My TT is about 8500# and I see 7-10 depending on the terrain.
Overall, a great truck and I'm very pleased with my decision to go back to gas. The lower initial purchase cost, lower cost of fuel at the pump and good mpg from this new age of gas motor really make for a great setup. To me the cutoff for diesel would be around 10,000#. The truck is easily capable of more and I'd have no problem doing it. It's just that if I were towing north of 10K often I'd want a diesel. For my usage and needs the gas is perfect.
