Which setup for best MPG on the Hemi

[Willyq711]

Hey all,

Looking at two preowned non-etorque Hemi's, both 2019's (Longhorns). I'm looking to get some feedback on which of these will give better gas mileage....

1. 2019 Longhorn, Hemi non-etorque, 2x4 with 3.92 axle.

2. 2019 Longhorn, Hemi non-etorque, 4x4 with 3.21 axle.

Most of my driving is 50/50 city/hwy and very little towing, if any. I do drive spirited at around 80+ on the Hwy.

The question here bis what's more beneficial for fuel economy... The weight savinga and lesser drive train work of the 2x4, or the lower gear ratio?

Thanks.

 

[vincentw56]

Hey all,

Looking at two preowned non-etorque Hemi's, both 2019's (Longhorns). I'm looking to get some feedback on which of these will give better gas mileage....

1. 2019 Longhorn, Hemi non-etorque, 2x4 with 3.92 axle.

2. 2019 Longhorn, Hemi non-etorque, 4x4 with 3.21 axle.

Most of my driving is 50/50 city/hwy and very little towing, if any. I do drive spirited at around 80+ on the Hwy.

The question here bis what's more beneficial for fuel economy... The weight savinga and lesser drive train work of the 2x4, or the lower gear ratio?

Thanks.

2x4s are for wood. 4x2s is for trucks.

Number 2 would probably give the best. But keep in mind you are probably only going to see a 1 or 2 MPH difference.

 

[beetlespin]

I have number 2 and regularly see 20-22 mpg.

 

[irishwake63]

if ya want a good 4x4 get a Jeep if ya want a gas efficient vehicle get a Prius if ya want a truck that will tow more get the 2X4 3:92

 

[Scram1500]

If you travel at 80+ the 3.21 will get the better mileage even with 4x4. That said the 3.92 2x4 would be a blast, unless it doesn't have limited slip then you could be gimped by wet grass

 

[Richard320]

I would guess it's gonna be a tossup.

I have 4x4 3.21. It's what I wanted because I anticipate moving somewhere with 80 mph speed limits once the wife retires. However, sometimes I get to drive that fast locally, and the truck will downshift on a 4% grade when I'm going 75-80. There's a post here that explains the math. 7th gear w/3.21 is the same RPM as 3.92 in 8th. So I haven't gained anything with the 3.21.

Your 50% city driving will benefit from the lower gears, because 3 tons is a lot of weight to get moving.

Where I have seen great fuel economy is on long drives on two lane highways or where the road is really flat. Then it's easy to get 21-22 mpg, so long as you keep the speed below 70.

 

[jkm312]

I have a 19 Laramie 4 x 4 with a 3.92 rear end. I ordered it that way on purpose. What I have found there is less gear shifting with the 3.92 when you are cruising down the highway, it stays in 8th gear most of the time when driving thru the rolling hills here in the midwest. When it does drop a gear or two on a grade it is always nice and solid. Drove it to the Carolina's and outer banks, it went right on by lots of cars and trucks thru the mountains in West Virginia and Virginia. I was in the 19 to 20 MPG for the trip, good enough for me. Running in town the MDS will stay on a little bit more than the 3.21.

What does matter more than you think are the size, weight and air pressure of the tires you are running , coupled with how much lead is embedded in your right foot. It's a truck, it's going to burn some gas, end of story.

 

[scottmoyer]

Please refer to this correctly. As stated, a 2x4 is a piece of lumber. 4x2 and 4x4 are proper terms for vehicles as the first number designates the number of wheels and the second number denotes how many are drive wheels

 

[1923bob]

Hey all,

Looking at two preowned non-etorque Hemi's, both 2019's (Longhorns). I'm looking to get some feedback on which of these will give better gas mileage....

1. 2019 Longhorn, Hemi non-etorque, 2x4 with 3.92 axle.

2. 2019 Longhorn, Hemi non-etorque, 4x4 with 3.21 axle.

Most of my driving is 50/50 city/hwy and very little towing, if any. I do drive spirited at around 80+ on the Hwy.

The question here bis what's more beneficial for fuel economy... The weight savinga and lesser drive train work of the 2x4, or the lower gear ratio?

Thanks.

I have 3.21 works great.

 

[Willwork4truck]

Just about all the posts above reflect my experience. I had a 2019 4x Ltd with stock 22's and 3.21 non-et. Best highway at 70 was touching 22. Most any smaller hill dropped me out of 8th.

Now I have a 23' Ltd 4x (basically the same truck) except it has the 3.92's. At the same speeds highway I get 20.5-21, no better. Slight hills it stays in 8th.

Around town there's probably no observable differences.

Buy the truck you like for its' overall condition, miles and options. Don't sweat the gears unless you tow, and then the low payloads hamper you with the higher trim RAM like a Longhorn.

Sure I'd like the 3.21 mileage again but I also like the 3.92 on hills.
If I lived in hilly/mountain country I'd stick with 3.92's.
Flatland? 3.21.
Tow much of anything (north of 6K GVW trailer) then 3.92's.
Tow heavy (8K or more trailers)? 2500 gasser long bed.
(I'm not into the cost and maintenance of diesels but understand why peeps like them.)

 

[dajogejr]

I had a 15 with a 3.92, now have a 23 with 3.21.
Mix of city and highway, 80ish like you said.
Very little towing? If it’s not very steep/lots of hills where you live.. 3.21 all day long.
Yes, if you’re doing 80 and you hit inclines, etc., it may hunt/downshift a bit.
But other than driving around town and getting heavy footed…where the 3.92 really shines (Other than towing)… you won’t miss it. I thought I would, but I don’t.

Unless it was a money decision and/or all I did was go job site to job site on good roads, no snow, etc., no way I’d own a truck without 4x4. But that’s me, in Metro Detroit.. where it’ll snow and be sunny on the same day..
If I was in the southern states… 4x2 would enter my thought process.
I don’t off road in my truck, a two track now and then… I have a Jeep for that
LOTS of good advice here from fellow members. It’s where you drive and how you drive..

 

[2021QCBH]

I tow frequently but at a max of about 4500 lbs so I wanted the highway benefit of 3.21s. Typically I’d have ordered 3.92s but the DT 5.7 trucks have revised 1-2 gear ratios for better low speed acceleration so I went with the 3.21 and love it.

If it’s not super windy in the flats pending speed it’ll return hand calculated 20-23 mpg highway.

I agree, around town there’s probably not an observable difference. Pending my week and the temperature my normal commute can be anywhere from 14-18 mpg city ish.

Also bear in mind, some people see wildly different MPG out of the 5.7s.