4x4 3.92 rear
Professional
Joined: Aug 2009
Posts: 245
Likes: 1
From: Pennsylvania
I am looking at a 2011 Ram 1500 CC 4x4. It has the 5.7 and 3.92 rear gears. It also has the anti slip differential and trailer brake controller. I am trying to get a little information on highway and fuel performance. How does that low of a gearing ride on the highway and is the MPG's really bad because of it?
Veteran
Joined: Jun 2012
Posts: 400
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From: Woodbury Tn
Exactly...as in similar to the truck he was looking at....not as in similar just because you have a hemi truck with different equipment. After rereading it I really am thinking the op was concerned about how high the truck would rev at highway speeds with the 3.92's and how the lower gear would affect mileage on the highway and then fuel performance in general
Last edited by Old Man with a hemi; Mar 16, 2014 at 10:47 PM.
Veteran
Joined: Jun 2012
Posts: 400
Likes: 0
From: Woodbury Tn
After reading this thread and all the posts many times...to the OP, it seems that there is a question about how 3.92 gears will perform on the highway. At 70 mph with 275-60-20 tires you will be turning around 2000 rpm, and if kept under that rpm you can still achieve fairly good mileage, with no considerable minuses by running this gear. Gas mileage claims vary by location, type of road driven, and your driving habits. Claims as high as 24 mpg have been claimed over 5000 ft altitude, but not an average mpg. The majority of posters seem to see mileages between 17-19 mpg on average, and these claims seem feasible. Others claim mileage under 15 which is also very possible depending on the things listed above and work being done, or in very cold climates. I'd say to you to read all these posts and make up your mind as to who you think is the most honest and who has the most believable posts
Rookie
Joined: Mar 2012
Posts: 68
Likes: 0
From: British Columbia, Canada
My truck is a 2010 crew cab with the 3.92 gearing 4x4 5sp auto and 87000km. cruising on the highway I average about 20-21MPG (imp. gal) I have gotten as good as 24 and in the colder wetter season usually about 18 mpg. I did find after 25000km my mileage jumped. At highway speeds 60 to 70 mph it is running about 1800 rpm. I pull a travel trailer that is about 6500lbs and with the 3.92s it pulls like a mule...just don't ask about mileage when pulling it is too depressing!
