Which affects gas mileage negatively more on a Hemi... Not having eTorque or having a 3.92 Rear?

[silver billet]

I can tell you right now the 3:92 is not affecting your gas mileage as much as you think. I have an eTorque with 3:21 and 4wd and I have yet to get more than 17-18 mpg on the freeway as well with cruise control set at the highway speed limit of 65 mph.

I see these types of comments all the time, but always they have 2 problems: first, your comparing apples to oranges. What you get, in your driving style with your average trip, can in no way be compared to anybody else. Unless you have driven exact same truck for a few months, with only difference being 3.92 vs 3.21, then you're just a single data point and you can't leap from that to "the difference may not be as much as you think". Because, for example, I regularly see 24+ mpg (computer calculated) in my highway usage. 3.21 gears. Again, can't compare it to you in the 3.21, never mind you with the 3.92.

Second problem; when we're talking 20 mpg, a decrease of 3 or 4 mpg seems tiny. But in reality it's a decrease of 15 to 20 percent. When you start at 15 mpg, a decrease of 2 or 3 mpg is a difference of 13 to 20 percent. Literally every mpg counts when the numbers are this small. If you said 40 mpg, well, each decrease there of 1 mpg is far less significant.

So don't look at the mpg by itself, look at the percentage you gain/lose and you might change your mind on whether the 3.21 is effective or not.

 

[Gen3CoupeTX]

Like others have said, the single biggest factor in your MPG is how you treat the throttle ... Your own driving style. I insisted on a 3.92, preferably without eTorque. I've seen 20+ when I'm trying to, and can see much less if I'm being more spirited. Get the combo that best serves your needs and/or desires!

 

[SpeedyV]

I think you make some good points, especially for city driving. On the highway though, etorque doesn't help and may even be a slight parasitic loss (plus added weight).

The EPA rated eTorque for slightly better economy than non-eTorque (1 mpg) on the highway. There's no evidence of any situation where eTorque performs worse.

That said, as I've posted in previous threads, the real-world combined advantage (per Fuelly) of eTorque is less than 1 mpg, not the 2 mpg claimed by the EPA. But trucks with eTorque do see an advantage, and I agree that it's more likely to show a meaningful benefit in stop-and-go driving.

And returning to the beginning of this thread, I'll say again that the choice of gearing will have a far more significant impact on real-world economy.

 

[YellowSled]

With same driving styles bottom line, 3.21 gears will yield better gas mileage than 3.92, eToque will yield better gas mileage than non-etorque. Your driving style will vary and will change with it. I personally opted for 3.21 and etorque as I will not be towing heavy loads and ill be a homedepot/lowes home stuff hauler.

 

[aimlowrobin]

I have owned several RAMS, and picked up an etorque with 321s last week. I have previously owned non etorque, both 322 and 392. I never really noticed much of any difference in any of the trucks, including towing heavy loads with 321s. My last two, I have added either pedal commander or pulsar and both those easily increased the take off "snappiness" of the 321s to 392s. All my trucks have been with 35 inch tires. Bottom line...I personally would not pass up a deal on a truck due to either the etorque or gears, if everything else was what I wanted.

 

[Granite2WD]

The EPA rated eTorque for slightly better economy than non-eTorque (1 mpg) on the highway. There's no evidence of any situation where eTorque performs worse.

That said, as I've posted in previous threads, the real-world combined advantage (per Fuelly) of eTorque is less than 1 mpg, not the 2 mpg claimed by the EPA. But trucks with eTorque do see an advantage, and I agree that it's more likely to show a meaningful benefit in stop-and-go driving.

And returning to the beginning of this thread, I'll say again that the choice of gearing will have a far more significant impact on real-world economy.

My understanding is etorque helps off the line from a standstill, helps with auto shut-off at stops, and helps fill torque between shifts. When would etorque be active on the highway?

I looked up how the EPA does highway rating tests and found the following:

"The "highway" program, on the other hand, is created to emulate rural and interstate freeway driving with a warmed-up engine, making no stops (both of which ensure maximum fuel economy). The vehicle is driven for 10 miles over a period of 12.5 minutes with an average speed of 48 mph and a top speed of 60 mph. Both fuel economy tests are performed with the vehicle's air conditioning and other accessories turned off."

To me, highway should be sustained 60 mph + speeds. If the max highway speed is 60 in their test, it makes sense why so many Ram owners complain about bad fuel economy. Even if they are driving 65 mph, they are exceeding the max EPA speed by a significant amount. Interesting.

 

[silver billet]

Yeah the EPA stuff is hit or miss. The best way to use the EPA, is to compare it against itself. So if you look at 2 trucks and the first truck EPA says 23 highway and second truck is 20 highway, well, the first truck will more than likely giver higher MPG for everybody who drives it.

But don't compare YOUR truck to EPA and expect to get those numbers. Just compare EPA truck rating vs another EPA truck rating to get a feel for how the trucks compare against eachother.

 

[SpeedyV]

My understanding is etorque helps off the line from a standstill, helps with auto shut-off at stops, and helps fill torque between shifts. When would etorque be active on the highway?

I looked up how the EPA does highway rating tests and found the following:

"The "highway" program, on the other hand, is created to emulate rural and interstate freeway driving with a warmed-up engine, making no stops (both of which ensure maximum fuel economy). The vehicle is driven for 10 miles over a period of 12.5 minutes with an average speed of 48 mph and a top speed of 60 mph. Both fuel economy tests are performed with the vehicle's air conditioning and other accessories turned off."

To me, highway should be sustained 60 mph + speeds. If the max highway speed is 60 in their test, it makes sense why so many Ram owners complain about bad fuel economy. Even if they are driving 65 mph, they are exceeding the max EPA speed by a significant amount. Interesting.

Yes - my only guess is that either the “shift-smoothing” or 48V efficiencies somehow gave a slight bump to eTorque in the test. But I agree that it doesn’t represent real-world highway driving.

 

[J-Cooz]

If you do a lot of city driving the etorque will definitely save you gas. I hate stop start systems but etorque is so smooth I love it. It's nice sitting a stop light and the truck is off, saving gas. When the light turns green you're on your way smoothly with zero delay.

I've sat in traffic in downtown Toronto and the truck stayed off for 3-4 minutes while I was waiting to move again

 

[yankeefan31569]

i get better gas milage with winter blend gas 89 hemi no eco 3.21 now that sunmer blend gas in the northeast is here i lost a bit

 

[Orion10182011]

Etorque would help for stop and go driving, the 3.92 may also help around town. Also losing weight will help MPG around town. Aerodynamics and 3.21 are you best bet at highway speeds.

 

[silver billet]

Don't be so sure that 3.92 is better around town. In the Jeep Grand Cherokee, they tuned the transmission in "ECO" mode so that the transmission starts from 2nd gear from a stop. Must be a reason for that, and the 3.21 would emulate that "taller ratio" more than the 3.92 would. The GC uses the exact same 3 engines and same ZF 8 speed transmission (maybe minor tweaks) too, though it is a little lighter than the Ram of course.

 

[WXman]

I find that most non-enthusiasts still do not understand what eTorque is. It is NOT a hybrid system. At no point in time can you drive on electric power. The only thing it does is aid the start/stop system during that first 1-2 MPH from a stop, and "smooth out transmission shifts" which is hard to detect on a ZF trans that already shifts smoothly. That's it. I don't see any logical or scientific way that it could possibly increase fuel economy in the real world.

And, any 0.003 MPG that you save will immediately be lost when that $1,400 MGU needs to be replaced out of warranty or the 48V supporting system fails.

I would suggest looking for a Pentastar or EcoDiesel if miles per gallon is what matters to you.

 

[SpeedyV]

I find that most non-enthusiasts still do not understand what eTorque is. It is NOT a hybrid system. At no point in time can you drive on electric power. The only thing it does is aid the start/stop system during that first 1-2 MPH from a stop, and "smooth out transmission shifts" which is hard to detect on a ZF trans that already shifts smoothly. That's it. I don't see any logical or scientific way that it could possibly increase fuel economy in the real world.

And, any 0.003 MPG that you save will immediately be lost when that $1,400 MGU needs to be replaced out of warranty or the 48V supporting system fails.

I would suggest looking for a Pentastar or EcoDiesel if miles per gallon is what matters to you.

It’s the definition of a “P0” hybrid, actually. And as you wrote, it enables stop/start, which...saves gas. Per Fuelly data, it appears to save 0.5-1 mpg on average. But I agree that most people seem to expect too much from it.

 

[Diddy Sanchez]

I have the etorque 3:92, 3400 miles is all, so maybe it will get better after a few more miles. In town I’ve gotten up to 18 mpg, however if I just do short trips like 2 miles to work and back it’s only like 15 mpg. The engine has to be hot, before the etorque really kicks in. Now for the kicker highway mpg so far best Ive gotten is 17, it’s rated at 22. That’s driving flat ground at 60 mpg. Not very good considering I paid 1200 more for the e torque. I really like the way the hemi pairs with the 3:92 gears, it’s like driving a high end sports car! I would say based on my truck the 3:92 mpg really kills the highway mpg. Good luck!

That low is crazy, I'm getting 15-17 on 3.92's w/etorque on 37's....also, the lack of traffic lately is padding my numbers bit, but still im impressed

 

[Runagun]

So changed my tires from the 22 inch ram optional rims to the stock 20's notice a 1+mpg improvement. Everything else stock 5.7 with etorque 3.21 rear end.

 

[BigD]

I'm averaging 19.6 mpg driving 50/50 city/highway with 5.7 Hemi 3.92 gears etorque. That's my average since I bought truck 2 months ago with 1,850 miles on it so far.

 

[ehk49]

5.7 Hemi, non e-torque with 3.92 gears here and I get 21+ on an all highway trip. I don't think you can ask for much more in a half ton truck. Of course that will change for me in the next 24 hours since the 6" Zone and 35s are getting installed as I write this.

 

[Wakesnowb]

5.7 Hemi, non e-torque with 3.92 gears and getting about 13mpg around town.