It depends on what you mean.
If comparing a 2WD Ram to an similar 4WD model driven in 2WD, the official highway numbers are 28 and 27.
If comparing a 4WD Ram in 2WD versus 4WD auto, probably less than 0.5 mpg.
If comparing a 4WD Ram in 2WD versus 4WD hi-range, probably a little over 1 mpg.
The weight penalty for adding 4WD is about 220 to 265 lbs depending on the model. That is a minor economy factor at highway speed where wind and rolling resistance are the biggest factors. Where the weight hurts is payload capacity and balance (front heavy with light loads).
I'm averaging 23 mpg with my 4x4 with 3:55's mostly highway. I have to really baby it to get 28 to 30 on the highway but that's no fun...
I'm not at full efficiency with only 1k on her and I haven't towed anything yet. I think the rings seated recently as well. Just before I fueled up the engine note changed (a little deeper sound).
The EVIC says different but my OCD makes me hand calculate every fill up.
I also have a tendency to crack the throttle once the turbo spools up to remind myself that the truck is powerful as the hesitation on take of is horrible... I HATE drive by wire!!!
I expect it will get 2 mpgs better once at full efficiency even with my frequent adrenalin rushes. This is not my first break in on an engine so I know I need to work the engine a bit more and ill start towing this week.
I can't see a 2 wheel drive getting much better with the amount of torque these trucks put out at just 2000 rpms and an 8 speed that keeps you right at the top of the torque curve no mater what speed your going.
"Add in" I also grabbed the protection package which added 2 pretty beefy skid plate I would add 80 pounds or so for those.
I don't know where you are from so that may be a factor. You speak of fuel mileage. Others have correctly told you it's not significant on the highway. I agree. Where it's significant is when you need four-wheel drive. You can sure burn lots of fuel when stuck and trying to get out. It can be quite expensive if you lose traction and wreck. Pulling a boat up a ramp can cost you both fuel and tires if you only have two-wheel drive. Wet grass and dirt trails can cost you lots of fuel and damage if you don't have four-wheel drive.
Then, if/when you sell, a two-wheel drive has fewer buyers that also may cost you.
If you use a truck, as a truck, a two-wheel drive pickup is not really a "truck".
I definitely agree with the captain on this. A 1-2 mpg hit for a 4x4 is well worth the price. I would never consider buying a 2 wheel drive truck even though 99% of the time it will be in 2wd. That being said I've been averaging 25mpg mixed and 29.5mpg highway at 70mph. My old Honda CRV that I had in college would be lucky to hit those numbers, and that's almost 50% better than my 2013 Tacoma, so I'm very happy.
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