Difference in gas mileage between the 3.21 and 3.92?

[Fmrchvy]

I recently returned from a cross country drive with some sizable mountain climbs and descends. I tended to drive a few over the listed speed limits of between 65 to 80mph and saw 17.5mpg to 18.8 mpg. I'm happy with that.

I'd much rather have the 3.92's added tow capability than the 3.21's marginal mpg improvement. The recent TFL truck utube video comparison between a 2019 Hemi Rebel 3.92 and the 2020 ED with 3.55 makes a strong argument to steer clear of 3.21 if you plan to tow/haul.

I watched that video, I don’t recall a mention of the 3.21 specifically at all. The reviewers spent their time discussing the Hemi and it’s towing power and never really addressed gearing other than to state what each truck was running.
After owning both, I don’t see a big difference between the two at all. Those in favor of mileage may believe they are going to save big on gas with the 3.21...they aren’t. Those in favor or torque may believe they will benefit big with 3.92...they won’t.

 

[Bearman95]

My 2020 four-wheel-drive sport with Hemi, no E torque, and 392 rear end got me 19.6 miles to the gallon today from Fort Worth Texas to 50 miles north of Denver Colorado. It was all interstate driving and the speed limit was anywhere from 60 to 75 depending on where they were doing road construction. The only time I got over the speed limit was passing. That was using 89 octane gas, I was pleased to say the least. All stock except for a back flip bed cover. It was 18.1 until I got into the higher elevation and then it jumped up to 19.6 before I ended my drive.

 

[Willwork4truck]

Oh, jeez, I already had my driver's license for several years when that 1966 Catalina was new.

Then you can join me in the old farts club!
All memories aside, the Detroit iron of the 60’s was a thrill, no fancy electronics and computers, just carbs, cams and fun. At least you could fix it when it broke. Now? Not very much.

 

[Dr. Jim]

Then you can join me in the old farts club!

Yes, I was afraid of that.

I totally agree about the 1960's. Bought my first new car in 1967 (Mustang). Three years later bought a 1970 Challenger. Sold the Mustang to my girlfriend. Two years later (1972), ended up marrying her to get that Mustang back! Still married to her (the love of my life) but I wish I had that Mustang and Challenger.

 

[Willwork4truck]

Yes, I was afraid of that.

I totally agree about the 1960's. Bought my first new car in 1967 (Mustang). Three years later bought a 1970 Challenger. Sold the Mustang to my girlfriend. Two years later (1972), ended up marrying her to get that Mustang back! Still married to her (the love of my life) but I wish I had that Mustang and Challenger.

ue car enthusiast, marries to get it back, ha ha. Glad for you that you got both!

Question. That Pontiac Catalina 2+2 had well over 300 hp and torque. It was somewhere in the 6 liter range. So how is it believed that we have “advanced” so much in 50 years?
A good v8 gas mill now has the same stats...

OK the longevity is better and we have emission controls but these new engines cost as much as the whole car did in the 60’s... hmmm.

 

[Adrianp89]

ue car enthusiast, marries to get it back, ha ha. Glad for you that you got both!

Question. That Pontiac Catalina 2+2 had well over 300 hp and torque. It was somewhere in the 6 liter range. So how is it believed that we have “advanced” so much in 50 years?
A good v8 gas mill now has the same stats...

OK the longevity is better and we have emission controls but these new engines cost as much as the whole car did in the 60’s... hmmm.

How they rated HP changed in '71 so there is that. Check out with excerpt "The immediate result was a dramatic drop in advertised power. For example, the mammoth 500 cu. in. (8,194 cc) engine in the Cadillac Eldorado fell from 400 gross horsepower (298 kW) in 1970 to only 235 net horsepower (175 kW) for 1971. "

They are also getting 300hp out of 4 cylinders, and making 500hp+ engines that get 30mpg in heavier cars I would say it has advanced quite a bit.

As far as price, again inflation isn't taken into account. A $3,000 (~Base MSRP) Catalina in 1965 would cost $24.5 today. Hard to put a comparison up but a Chevy Malibu starts at ~23 - car prices really haven't changed a whole lot.

 

[Willwork4truck]

How they rated HP changed in '71 so there is that. Check out with excerpt "The immediate result was a dramatic drop in advertised power. For example, the mammoth 500 cu. in. (8,194 cc) engine in the Cadillac Eldorado fell from 400 gross horsepower (298 kW) in 1970 to only 235 net horsepower (175 kW) for 1971. "

They are also getting 300hp out of 4 cylinders, and making 500hp+ engines that get 30mpg in heavier cars I would say it has advanced quite a bit.

As far as price, again inflation isn't taken into account. A $3,000 (~Base MSRP) Catalina in 1965 would cost $24.5 today. Hard to put a comparison up but a Chevy Malibu starts at ~23 - car prices really haven't changed a whole lot.

Edit - where did you find that? My googled research (from:
Last Time Around: The 1971–1976 Cadillac Eldorado ...

https://ateupwithmotor.com › model-histories › cadillac-eldorado-convertible...

on the same topic found this: "When the 500 cu. in. version debuted in the 1970 Eldorado, it was rated at a whopping 400 horsepower (298 kW) and 550 lb-ft (745 N-m) of torque, although a drop in compression ratio for 1971 cut the big engine's output to 365 hp (272 kW) and 535 lb-ft (725 N-m).Apr 8, 2008 "

Big difference between 365 and 235...
Of course safety improvements cannot be priced either. Still seems like we've not advanced as much in 60 years as we did the 60 years from 1900's - 1960's. Oh well, the younger generation probably hasn't ever even seen a car older than the 80's so, move over old man...

 

[Fastman21]

All I can say is my Rebel with eTorque and the tow package (3.92) is averaging 12 mpg after 6,000 miles..albeit about 90% city driving. FCA has been absolutely no help in resolving the far below EPA stated numbers of 17/19/22. Hoping someone will eventually file a class-action lawsuit against them for misrepresenting the mileage numbers.

Rebel , Hemi , Etorque , 3.92 Sits at 16mpg , just over 9000 miles.

 

[Jim L]

only have had My 2020 laramie with 3.92 rear end which I ordered for two weeks. Pulled my bassboat yesterday for first time with just over 500 miles on truck and was happy with 12.5 mpg averaging 70 mph which is actually better than my Chevy 6.2 got so very happy. It might get even better once broke in but again happy cause I buy a truck for towing so I want the power. Awesome truck and very smooth driving

 

[Willwork4truck]

only have had My 2020 laramie with 3.92 rear end which I ordered for two weeks. Pulled my bassboat yesterday for first time with just over 500 miles on truck and was happy with 12.5 mpg averaging 70 mph which is actually better than my Chevy 6.2 got so very happy. It might get even better once broke in but again happy cause I buy a truck for towing so I want the power. Awesome truck and very smooth driving

Good news. Yes it has been reported that the gas mileage slowly improves, I’ve read between 4 and 7K.
I only have 4400 miles on mine and haven’t noticed any change In mpg on the highway, the variables of fuel quality, average speed and the type of road seem to mask any small break-in changes for me.

 

[deer]

Well I have a 2019 Ram 1500 Bighorn North addition level 2 5.7- 321 rear it has 2500 miles on it and i'm getting 14 miles city and highway . love the truck but not the MPG.

 

[AtlasRam1500]

After owning a 19 Laramie 4x4 with the 5.7 3.21 and Currently a 19 Limited 4x4 5.7 3.92 overall i was happier with the driveability of the Laramie it to me seem it was suited better for me. 15/19mpg Limited 13.5/17mpg
Wish the Limited hand the 3,21

 

[derp]

3.92, 15.4mpg on the dash today.

the first few weeks I had it I was at 12.8. either it's breaking in or I'm getting more easy on the pedal. I've also already done my first oil change 2kmi early, that may have changed things since the shipping oil is out.

 

[Willwork4truck]

Good news. Yes it has been reported that the gas mileage slowly improves, I’ve read between 4 and 7K.
I only have 4400 miles on mine and haven’t noticed any change In mpg on the highway, the variables of fuel quality, average speed and the type of road seem to mask any small break-in changes for me.

UPDATE - 6600 miles, no changes in mpg over the same roads.

 

[Willwork4truck]

After owning a 19 Laramie 4x4 with the 5.7 3.21 and Currently a 19 Limited 4x4 5.7 3.92 overall i was happier with the driveability of the Laramie it to me seem it was suited better for me. 15/19mpg Limited 13.5/17mpg
Wish the Limited hand the 3,21

I've got the 3.21 Ltd non ET and while I appreciate the lower (extra overdrive) gearing, it does tend to downshift from 8th to 7th often, usually small hills or moderate acceleration, so in that sense the 3.92 would likely not downshift and been better. I originally spec'd a 3.92 but that deal fell through (twice) so I gave up and bought a local 3.21. Came out of a 2.7 ecoboost F150 so that kinda spoiled me, tons of torque, hardy ever downshifted.

 

[upwindstorm]

i only seem to muster 14mpg max with mixed driving and a daily commute of 40 miles driving 70mph . i have the 5.7 non e tourqe with the 3.21

 

[whsk12]

12.9 to 13.4 mostly in town-it is a truck!

 

[Willwork4truck]

12.9 to 13.4 mostly in town-it is a truck!

That's what my son gets, with his non ET with 3.21's in town.
I do better but then the people behind me keep giving me the "RAM is #1" gesture. Seems to be alot of RAM supporters out there...

 

[eyeguy]

I can hold 16mpg with in town driving only 3 miles to and from work. So not even getting warmed up... I notice even coasting at 30 mph i only get about 20-25 mpg when its trying to warm up dumping extra fuel in. if I go just a few more miles and coast the instant mpg at a 30 mph coast goes to nearly 99. I have a 2020 laramie org 3.21 non et. Wish they made a 3.55 for 60 mph driving. 60 is at that awkward rpm in 8th. A little boggy. 65-70 mph it does better.

 

[Willwork4truck]

I can hold 16mpg with in town driving only 3 miles to and from work. So not even getting warmed up... I notice even coasting at 30 mph i only get about 20-25 mpg when its trying to warm up dumping extra fuel in. if I go just a few more miles and coast the instant mpg at a 30 mph coast goes to nearly 99. I have a 2020 laramie org 3.21 non et. Wish they made a 3.55 for 60 mph driving. 60 is at that awkward rpm in 8th. A little boggy. 65-70 mph it does better.

I know. i’ve probably said it 2 dozen times that dropping the 3.55 was a dumb move. I’m sure the FCA chairman will be calling me to ask what I think soon...