I just bought a used 2012 ram 2500ST, hemi, 4x4, crew cab, long box with 3.73 gears and 68k miles, stock tires no lift. I pull a 24` travel trailer that's 3500 empty. We dont use any water in it so pretty much just food and cloths and a few odds and ends, so I`ll say it weighs around 4000 full. The bed had maybe 200lbs + cap. We just got back from a 700 mile trip from lower Wisconsin to U.P. Michigan and back, so no real hills. Computer said 7.2-7.8 mpg, my calculations said right around the same, which I think is terrible! I was keeping the speed between 70-75mph(speed limit is 70). The truck seemed to not be happy in OD and would stay in 5th or 6th. I was playing around between using tow/haul and not using it or just putting it in 6th and leaving it there and nothing really changed the mpg. Last month we did this exact same trip with my now traded in 2009 F150 , same camper and gear and ave 12.5mpg at worst! How can this truck be so much different?! And what can I do to make it get better mpgs while towing? When the truck is empty I see 13-16mpg which I like. Would a tuner help? if so which one? help!