pulled my 14x7 enclosed trailer today (about 3000lbs) about 90% highway in regular mode with my '07 ram 1500 QC 4x4 4.7 with 4800 miles on it and 3.92s i got 9 mpg with the cruise set at about 62 mph. this was semi flat with small rolling hills.
i pulled the same trailer to indiana when i first got the truck in tow/haul mode and got 9.5 on flat ground. makes me wonder if its better to put it in tow/haul mode (mpg wise).

 

Very likely, although my '03 doesn't have tow/haul. That's a fair-sized trailer. Let the mileage suffer, if it means keeping the truck healthy.

 

My truck also get better mileage when I drive around in tow haul mode. Especially if I drive aggresively.

Just for curiousity if you have that big of a trailer what are you hauling with it and why didn't you get the Hemi instead of the 4.7?

I have the 4.7 also just wondering.

 

i haul my sons race karts and probably only have about 1000-1500lbs of equipment in the trailer. it weighs about 2500 empty but this trip was only partially loaded so was probably 3000-3500. the heaviest i'll pull is probably 4000 and the 4.7 is rated well beyond that and i didn't feel i needed to spend an extra $1000 for the hemi. i have 2 neighbors that have or have had hemis. the one got rid if his '06 hemi to get an identical '07 4.7 because he complained about the mileage. he claims his new one is way better. the other one has an '04 that he said is a gas hog. looking back i kinda wish i would've got the hemi but too late now.
also, i've pulled heavier loads with my old chevy 305 and my old dodge 318 with no problem so i figured i would've been ok. i've seen guys pull trailers this size with little toyota tundras and chevy s-10s.

 

ive been pulling a 6-7k pd horse trailer, and a travel trailer. i know i am going the 4.10 route. that and the one wheel peel is driving me crazy, might as well do gears while i am in there.

edit...

but to answer your question, i do get better mpg, by about 1mpg in town and on hills with tow haul mode on.