I bought a 2015 RAM 1500, 4WD, Crew Cab with 10,800 miles on it (was a fleet/rental before I got it from Carmax). Tradesman trim, and V-6 power. I originally bought it with the idea of hauling a 1500 pound fishing boat (boat and trailer) on "long" trips, to go fishing in distant states, because, well, why not? Before the year was up, I had purchased a John Deere 1025 sub-compact diesel tractor and a flat bed "car hauler" trailer to haul it about 300 miles, several times per year. I got electric brakes on the trailer, and added "load booster" bump stops to replace the stock axle bumpers, and help keep it level.
I get about 24 mpg on state/federal 4-lane highways in cruise control at 55-65 mph. Slow down just a bit and it's a reliable 23+, and about 20-21 at 70 or more, no trailer. I have a Leer camper shell over the bed, and am usually hauling about 400 pounds of people and dogs and at least 500 pounds of tools in the cargo bed. The 8-speed transmission combined with the V-6 has plenty of power for any kind of normal highway driving.
Add the boat trailer, and it's almost unnoticeable. Mileage drops "some" but not "a lot."
Add the flat bed with the tractor (around 6000 pounds total, with truck hauling capacity of 7000 pounds "by the book,") and the mileage drops to about 14. If I had known I was going to haul that heavy trailer, I would have gone for the Hemi, but, for my 2-3 times a year moving the tractor 300 miles, it has been perfectly fine (from Chattanooga Tn to near Albany, Georgia). I have put the truck in 4WD Low range to move it all up and down my STEEP Tennessee driveway, but otherwise, I believe I value the good mileage above the extra horsepower that the Hemi would provide. I will probably buy a Hemi next time, especially if gas prices stay down, but for now, the V-6 with 8-speed transmission has been perfectly adequate in the places I've had to haul the heavier trailer. If I had to haul the heavier load every day, there's no doubt that a Hemi would be preferable, simply because durability is probably better when you're not operating the engine and transmission near the upper limits of their capacity.
If I end up not needing to haul the tractor around from state to state (which is probable) the V-6 would be my preference for people, dogs, gear and the fishing boat, simply because the gas mileage is better with the smaller engine.
I'm also not one of those guys who drives like NASCAR wanna-bees, so it's the utility and economy of the truck that I like. It's my "go to" vehicle for long trips (other car is a 2016 Subaru Forester) despite the Subaru's mileage (up to 36 on the interstate in cruise control) because I can carry a ton of stuff, two big dogs in the crew cab back seat, and it's probably more survivable in a crash, should that occur.
I'd say. think about what you are 'reasonably' going to do with the truck, and then pick the engine that gives you the utility you want from it. V-6 is going to be better mileage around town, no doubt, but Hemi is going to be better on the highway, doing 80, if that's your thing.
