mpg of 5.7 with 8 speed 3:92 vs 3:55

[monkers]

I tried searching, but couldnt find anything, I am looking for some first hand details of mpg with the 5.7 Hemi with 8 speed and 3:92 rear end versus the 3:55 rear end. My truck now is a gmc 2500 HD with 6.0 & 4:10, I did drive one 2013 Ram 5.7 8 speed with the 3:55s, but it was just a 5 mile test drive all flat ground, no hills etc....... I will be towing only a handfull of times a year, biggest thing I have to tow is a 3 place inline alum snowmobile trailer.
Any help or insight would be great, thank you guys... I am looking for Quad Cab, 4x4

 

[Burla]

Maybe none difference around the city, were you will loose it is on highway. Good news is with the 8 speed that will probably be minimal too. Whatever the small loss you will have it is way worth it, I hate my 3.55 and when I drive my friends Ram it has so much early power. Especially if you are towing anything, it is a no brainier but you might want your 4:10 too.

 

[cajun87]

I have the 4x4 5.7 8speed and 3.92's i get ave 15 in town and ave 17 on interstate. At 60mph i get 20 ave. This is on flat ground and summer time heat on reg gas.

 

[cajun87]

Pulling my bass boat at 70mph i get 14 mpg ave.

 

[monkers]

Thanks guys, Im used to the 4:10s so going to the 3:55s would probably be pretty noticeable to me. And at 15 mpg its still better than my GMC

 

[Burla]

The only reason I went with 3.55's was because I got the sickest deal on my 4x4 Hemi off the showroom for 24k, At least I got the Hemi with all that power that makes up for a lot, but those 3.55's just plain suck. You wont regret going the other way. Cajun's mileage is way better then mine, 2010 6 speed Ram gets nowhere near that.

 

[billybob12]

My 2012 1500 4x4 6 speed with 3.55s avg is 16mpg. City it gets 15 and 19.5 on the highway running 80mph.

Sent from my SCH-I545 using Tapatalk 2

 

[RamHemi5.7]

C'mon Burla! Ya hate the 3.55's that much? My 2013 has the 8 speed with 3.55's. I think it's a great combo. But I also am not seeing the high 17-18 MPG's you guys are quoting. I'm more like 15-16. (365 miles a tank)

However, I've also never driven another Ram with the 3.92's....I maybe should try it out one day...lol

Is there really that much of a difference between the two?

EDIT: im getting about 365 miles a tank, not 265...

 

[Diller]

Not sure what you guys are use to driving but my 5.7 8speed and 3.21s drives fantastic. And pull my race car and trailer as well as my F250 with 3.73s.

 

[LovMyRam]

I never understood why people buying a big v8 truck worry about fuel consumption. Especially when purchasing a 4x4 AND be doing your ocassional towing. I do know you'll be getting better than your 6.0 with 4.10's for sure.

 

[dmclone]

After 4,000 miles and about 60% highway driving, I'm right at 17mpg mostly using 89 E10. 3:55 , Hemi, and 8 speed combo. I usually drive between 75-80 on the highway. If you back it down to around 60-65 it makes a big difference.

 

[Chewy]

I never understood why people buying a big v8 truck worry about fuel consumption. Especially when purchasing a 4x4 AND be doing your ocassional towing. I do know you'll be getting better than your 6.0 with 4.10's for sure.

It's not worrying as much as trying to achieve the best possible MPG.


I have the V8 and 3.92's with the A8 and have never seen less than 15.5 MPG. My truck has a little over 2000 miles on it and I run dino oil. None of that fancy pants stuff for this engine.

 

[loveracing1988]

I never understood why people buying a big v8 truck worry about fuel consumption. Especially when purchasing a 4x4 AND be doing your ocassional towing. I do know you'll be getting better than your 6.0 with 4.10's for sure.

I just expect it to get what the sticker says, every other vehicle I've had has been able to get those numbers or better.
The highest I've ever seen on mine is 17.3 and that was almost 100% highway. I'm averaging 15.9 through 3600 miles according to fuelly. All of those miles about 75 percent of them are highway. I didn't buy the truck for fuel mileage but I'm getting no better than my bosses 2001 F 250 with the 5.4, yes it is 2wd but still a bigger truck.

 

[Chewy]

I just expect it to get what the sticker says, every other vehicle I've had has been able to get those numbers or better.
The highest I've ever seen on mine is 17.3 and that was almost 100% highway. I'm averaging 15.9 through 3600 miles according to fuelly. All of those miles about 75 percent of them are highway. I didn't buy the truck for fuel mileage but I'm getting no better than my bosses 2001 F 250 with the 5.4, yes it is 2wd but still a bigger truck.

Are you going the same speed as the tests they do to garner those MPG's? If I went 65mph I could get considerably better MPG's.

2WD helps a LOT, not to mention the fact that he may drive completely different than you.

 

[Remoth]

Youd probably need to run it on a dyno to get sticker mileage....

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[AirborneSilva]

I have 392's, on my last fill up I was getting just over 17.5 MPG's (calculated by hand), I probably dive 70 - 80% Hwy but drive 65 - 75 MPH with some WOT short runs getting around morons whom can't drive for ****...

EDIT: oh it should also be known that I have less than 4400 miles on my Ram too.

 

[loveracing1988]

Are you going the same speed as the tests they do to garner those MPG's? If I went 65mph I could get considerably better MPG's.

2WD helps a LOT, not to mention the fact that he may drive completely different than you.

If I never got the mileage a vehicle was rated for I would understand. This is the only vehicle I have ever driven though that no matter what I do I cannot get either the combined mileage or the highway mileage. I drive 65 mph to work every night btw, only maybe once every 2 to 3 weeks do I drive 70 mph.

 

[AirborneSilva]

If I never got the mileage a vehicle was rated for I would understand. This is the only vehicle I have ever driven though that no matter what I do I cannot get either the combined mileage or the highway mileage. I drive 65 mph to work every night btw, only maybe once every 2 to 3 weeks do I drive 70 mph.

Did you know that the EPA sets the MPG's not the manufacturer? if you have anyone to be upset with be upset with your government (well unless you're Canadian then you can just hate the US government for something else - wait that works for US citizens too)...

 

[mudjunky]

meh 17 mpg isn't bad I get I get 15l per 100 km which addes up to aprox 550 km per tank which is almost exactly what the window sticker is

oops forgot to mention 2013 5.7 hemi 8 speed lifted on 35s

 

[RamHemi5.7]

so question,

would it be correct to assume that a 3.92 gear would help mileage for city driving as apposed to the 3.55? (lots of stop signs, stop lights, and horse crap like that here in the bay area, california)