mpg's with a 3.92 rear end

I'm thinking of getting a new Ram with a hemi 5.7 with the 6 speed and with a 3.92 rear end and would like to know if anyone can let me know what the mpg's are. The sticker says 19 but it also say depending on options. Thanks.

Highway or city? Mostly city and stock tires I was getting about 13.8 with 3.92s. My brother in law gets high 17s on the highway with his 3.92s, and he just has a K&N intake.

It really depends on how you drive it, I get 10 in NYC, but that is the worst of the worst in terms of stop and go, lights, etc

When I hop on the highway I will usually set the cruise around 65+/- and get 20 more or less. Of course I am trusting that the EVIC is feeding me the true mileage, which I highly doubt it is, but I don't think it is too far off.

My truck is bone stock except for the bumper which probably makes my gas mielage a little worse, although I didn't really notice when I put it on.

with the 6 speed, I'd get the 3.92's over the 3.55's for sure...I have the 3.55's and wished I did 3.92's...you wont see much difference in gas mileage between the two.

3.92s, 5.7 QC 4x4 i got around 13-15 in town and 17-18 on highway. now with 35s, exhaust, intake and a fully loaded toolbox i get around 12 in town and 15-16 on highway. but like said before it depends on how heavy your right foot is. i got 10 in town right after i put exhaust and a intake in lol

i get 13 mpg no matter how i drive. but i also have under 1000 miles on the truck...

welcome to RF. I moved this the the tech section

Graygoose said:

with the 6 speed, I'd get the 3.92's over the 3.55's for sure...I have the 3.55's and wished I did 3.92's...you wont see much difference in gas mileage between the two.

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x2 when I ordered my '97 I caught all kinds of drama from people telling me how foolish it was to order 3.92s but 140K miles never killed me MPG-wise.

If it makes you feel any better, when I bought my 2010 Hemi, I was pulling the same MPG as my '97 with 155 more HP, 4 doors and about a ton more of truck.

3.92s will net you better MPG around town and in hilly/mountainous areas. If you drive accordingly. You will lose a bit on flat highway. But the difference is probably pretty slight all around.

3.92's give you a considerable bump in towing capacity. They will give you better final drive of course if you lift it with larger tires. Not a lot of drawbacks really.

I get 22-24 mpg hwy in the mountains if I baby it and actually do the speed limit, and that is with 3.92's. Lately I have been working a lot though and never get to drive my truck, soooo my foot tends to be a little heavier when I do get to drive it which ruins my fuel economy.

My 2012 is totally stock with 3.92's and with over 5,*** miles, my actual calculated avg mileage is 17 mpgs. I've had fillips run anywhere from 15.2 - 18.9 mpgs. I find the EVIC computer estimates about 1 mpg over what I'm actually getting.

IHRedRules said:

My 2012 is totally stock with 3.92's and with over 5,*** miles, my actual calculated avg mileage is 17 mpgs. I've had fillips run anywhere from 15.2 - 18.9 mpgs. I find the EVIC computer estimates about 1 mpg over what I'm actually getting.

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Yeah, I always calculate by hand. The EVIC isn't completely accurate.

Another point, the EVIC computes using the last value before reset as a starting point. I hit reset twice to start at 0 mpg rather than build on my last tankful.

Sagebrush2500 said:

Yeah, I always calculate by hand. The EVIC isn't completely accurate.

Another point, the EVIC computes using the last value before reset as a starting point. I hit reset twice to start at 0 mpg rather than build on my last tankful.

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Yeah I do the same thing. I average about 16mpg with my 3.92s Its a good mix between city and highway.

I've got around 15,000 miles on my 2011.

I have a '12 Hemi CC with 3.92 and stock 20's and I get roughly 17.5-20 mpg on the hwy depending on how I drive and 13-15 mpg city also depending on how I drive. I have a volant CAI but that is about it. I have 9K on my truck

I have a 2011 with 3.92 gears and 22' rims. I get 13.5-15 city, and 17-19mpg highway.

Volant, ported TB, catch can and 14" magnaflow are my only performance mods.

Don't fear the gear...3.92. Your gas avg will be better then the 3.55....truck won't have to work as hard to get it moving with the 3.92!

Just for another point of reference, my stock Power Wagon with 4.56's and 33" tires gets 12 in the city and 16 on the highway (with a full size 4 wheeler in the back). I have the 6 speed tranny.

14-16 city and 17-19 highway, 70-72mph with cruise on ive gotten 19.2 several days. I also run a tonneau cover which helps IMO.

dogcar3 said:

Just for another point of reference, my stock Power Wagon with 4.56's and 33" tires gets 12 in the city and 16 on the highway (with a full size 4 wheeler in the back). I have the 6 speed tranny.

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Lucky you lately ive been averaging 11.2 city around 13 hwy on the evic but with 4.10's on a single cab

Sometimes i get jealous of yalls mpg lol

Not sure if i have magic gas around here or what but with my 3.55 lsd. my worst tank so far was 15.3 all city. I usually average 16.8-17.2 city and anywhere from 19.9-24.6 highway (depends if im going 60 or 90) and my truck is 2012 crewcab sport 4wd w/tow mirrors, side steps stock 20's tonneau cover and about 200lbs of junk in it.

Compared to my friends trucks with 3.92 im usually between 1-3mpg better city and 2-4 highway. (about 2.5 mpg average) I consistantly am between 50-100 miles more per tank.

I will say the 3.92 is quicker off the line 0-60 they beat me by about 2 truck legnths from a dig not so much I usually catch/pass them when they shift from 1st to 2nd because I can hold first for about 9mph extra over them then keep the lead or stay even after that. quarter mile times are about .4 different from standing start. about even to .1 from a roll

This is my experiance take it for what its worth.


oh and a little math for thought say on the low end 1.5 mpg difference on a 32 gallon tank

1.5x32=48, 48mi per tank.
lets call it 14.5 average mpg on 3.92
48/14.5=3.3 extra gallons per tank
3.3x$3.90(chicago gas sucks)=$ 12.87 extra per tank

or on a bigger scale say 15000mi per year
15000/14.5=1034gallons per year
15000/16=937 gallons per year
1034-937=97 gal EXTRA per year
97x3.9=$378 Extra per year

now times that by 10 years and you are at $3780.00 extra in gas on the low end average if gas prices never change from their current point. Just food for thought.

All good to know.
We average about 15mpg with mixed driving, and saw about 10mpg while towing for the first time on the weekend, in strong winds.
Seems like thats not bad.