Horrific Gas Mileage Hemi eTorque

[rvsixer]

The 2019 Ram 1500 manual does not touch upon it, but straight from the 2018 Grand Cherokee manual. With ECO mode ON:
"For vehicles equipped with the 5.7L
Hemi, 4 cylinder mode will be enabled
under certain conditions"

I take that to mean, with ECO mode OFF, MDS will not become active. With ECO mode on, MDS can and may become active. So direct correlation.

 

[Kidder]

According to the regional technical support that I had my salesman contact when I wasn't seeing the ECO light come on this isn't true. As of 19 they directly correlate.

Where is the documentation? I know on my 2011, Eco meant nothing other than you were driving economically according to the ecu. I see it acting no differently now.

 

[Kidder]

The 2019 Ram 1500 manual does not touch upon it, but straight from the 2018 Grand Cherokee manual. With ECO mode ON:
"For vehicles equipped with the 5.7L
Hemi, 4 cylinder mode will be enabled
under certain conditions"

I take that to mean, with ECO mode OFF, MDS will not become active. With ECO mode on, MDS can and may become active. So direct correlation.

Fair enough.

 

[Kidder]

They (FCA) should implement it that when MDS is engaged, the Eco light comes on.

 

[SpeedyV]

According to the regional technical support that I had my salesman contact when I wasn't seeing the ECO light come on this isn't true. As of 19 they directly correlate.

FWIW...I hear the change in sound when the truck goes in/out of MDS, and it directly correlates with the ECO light turning on/off. I’ve always presumed the light simply acknowledges MDS behavior.

 

[Kidder]

FWIW...I hear the change in sound when the truck goes in/out of MDS, and it directly correlates with the ECO light turning on/off. I’ve always presumed the light simply acknowledges MDS behavior.

It does not. It can be simply that you're driving "economically". The light can be on without MDS engaged.

 

[SpeedyV]

It does not. It can be simply that you're driving "economically". The light can be on without MDS engaged.

Please provide documentation of this. A quick internet search shows a variety of opinions—some matching your statement, and some stating that ECO Mode simply means MDS is active. Either way, my empirical evidence is that I ONLY see the light when my truck goes into 4-cylinder mode, no matter how much I 'baby' the throttle.

The owner's manual (v5) isn't helpful. It mentions the "ECO Mode" indicator light on page 187, but it does not define this mode. On page 333, the manual mentions "Fuel Saver Technology" (MDS), but does not make any correlation between this and "ECO Mode". And pages 566, 589, and 614 mention the ability to turn on/off "Fuel Saver Display" for different UConnect systems. That's it.

 

[RAM805]

I have ~1100 miles on my '19 Limited 4x4 w/ 3.92, no bed cover, 5.7L non-e-torque. I drive pretty conservatively, mostly CITY miles, and fill w/ 91 oct. OEM 22" rims w/ OEM all season tires (not off road). Car computer says ~12.2 to 12.4 avg MPG. Yikes!

I am pretty much right there as well, avg. ~13 mpg, all city, short trips, running 87 octane.

 

[Michael_D]

5.7 e-torque. 3.21 gears. Offroad package. Premium fuel every fill up. (if you have ever logged knock retard with HP Tuners and 87 octane with any modern V8, you'd use it too).

I drove my truck from Idaho, up through Canada and home in Alaska. Roughly 3200 miles. I went through Banff and Jasper. Lot's of mountains.... In Idaho, on relatively flat stretches of road, and running 72 mph set on cruise control, I would see 21 mpg. That's as good as it got, ever. Through the Yukon, with questionable fuel quality and pretty large aggregate roads (rough surface), it dropped to 15.5 mph. Same average speed. Once I got back to the states and on better roads, I have been averaging 17.5 -18.1 mpg.

My last truck was a 2015 Sierra Denali, 6.2 ltr and eight-speed. 3.22 gears. Milage was slightly better with the GMC. I think it is due to the 6.2 having more low rpm torque. I would rarely downshift to 7th, whereas the RAM does all the time.

If you pull up the MPG screen on the display, and make sure instant is enabled (right arrow), you will see that when ECO is engaged, instant MPG will go up to 99. I'm pretty sure ECO is just cylinder deactivation.

 

[MJB4450]

Where is the documentation? I know on my 2011, Eco meant nothing other than you were driving economically according to the ecu. I see it acting no differently now.

On my 2015 the ECO light has never, ever come on when I have MDS turned off in eighth gear. It comes on when I feel MDS engage but never otherwise.

 

[19llhpb]

Hand calculated every tankful I am averaging around 16 mpg give or take a tenth or two on any given tankful. Roughly a 60/40 mix of rural short trip two lane highway or country roads and in town stop and go. That is 87 octane and you can see my truck details in my signature. It is a fairly heavy truck with the options, accessories, and items I keep on the truck. Have 5,100 miles on it now and I have been fairly easy on it.

 

[768mph]

5.7 e-torque. 3.21 gears. Offroad package. Premium fuel every fill up. (if you have ever logged knock retard with HP Tuners and 87 octane with any modern V8, you'd use it too).

I drove my truck from Idaho, up through Canada and home in Alaska. Roughly 3200 miles. I went through Banff and Jasper. Lot's of mountains.... In Idaho, on relatively flat stretches of road, and running 72 mph set on cruise control, I would see 21 mpg. That's as good as it got, ever. Through the Yukon, with questionable fuel quality and pretty large aggregate roads (rough surface), it dropped to 15.5 mph. Same average speed. Once I got back to the states and on better roads, I have been averaging 17.5 -18.1 mpg.

My last truck was a 2015 Sierra Denali, 6.2 ltr and eight-speed. 3.22 gears. Milage was slightly better with the GMC. I think it is due to the 6.2 having more low rpm torque. I would rarely downshift to 7th, whereas the RAM does all the time.

If you pull up the MPG screen on the display, and make sure instant is enabled (right arrow), you will see that when ECO is engaged, instant MPG will go up to 99. I'm pretty sure ECO is just cylinder deactivation.

I have 3.92 gears and my wife’s 19 BH has 3.21. Hers always downshifts to 7th whereas mine never does on the hwy; even climbing hills.
The 6.2 and 3.23 gears is a good combo. And right in line with the 5.7 and 3.92. Both do around 2K rpms at 70 in 8th gear.

 

[RT70808]

I am pretty much right there as well, avg. ~13 mpg, all city, short trips, running 87 octane.

That’s about what I’m getting 12.5/13 city. Limited no etourque and 3.21 gears.
16-17hwy and boat towing on slow 55/60 two lane roads.

 

[Ramit392]

Running Laramie 4x4 with air Suspension ,E Torque,3.92 combination driving more Hiway than in town like 70%/30% getting 19.8 mpg. on open road run about 63 mph with cruse on.

 

[Rustydodge]

My understanding of ECO (based on 4th gen and how my truck works)

For V8
ECO light comes on whenever MDS is active. Can disable ECO/MDS by pressing (-) on the steering wheel to select manually highest gear the trans can use. If you select 8th, all gears can be used normally, just without ECO/MDS ever being active.

For V6
ECO light come on whenever coasting.

I would assume, for V8 for 5th gen, this would continue. ECO light only on when MDS is active. I could be wrong.

 

[Vincey2kr1]

Went about 70 miles had a tail wind of 15-20mph and got 25mpg . V8 hemi etorque 3.21 gears. 89 octane. Think this was a rare occasion though flat highway and Kansas tail wind I'm usually getting 22mpg highway and 19 City.

 

[lowell3170]

I read every post/replies to my orignal post. I must say, I feel better!

A couple questions came up, (answers are
1) my gearing is 3.92
2) Rebel 4X4
3) I drive like an old lady
4) etorque
5) city mpg is running 13.5 on evic, about 13.0 hand calculated
6) HWY mileage 14.8 - 15.0 on evic, but about 14.3 hand calculated

My observations on my 1,600 mile trip: tank of mid-grade 89 octane had worse mileage than tank(s) with 87 octane, driving it easy, or spirited wielded very little mileage differences.
My driving conditions were optimum (virtually no wind, no rain, mild to warm temperatures).

While I knew the Monroney sticker stated 17 mpg city/ 22 mpg hwy, I fully expected worse than that, but not nearly as bad as I had gotten.

I anticipated about 15 mpg city/18-19 mpg hwy. I guess now I know that was overly optimistic.

As for my dealer, I hit a dead end. I went round and round with service tech who made every excuse possible to sell me on it being normal mileage. So, looking for a new dealer.

Those 3.92's are costing you 3 to 5 mpg over the 3.21 rear's.

 

[MrHankbot]

Those 3.92's are costing you 3 to 5 mpg over the 3.21 rear's.

Is it really that much? My impression from reading before I made my order was that it was more like 2mpg. If it's truly 5mpg less I'll wish I ordered the 3.21 diff.

 

[DaYooper]

Is it really that much? My impression from reading before I made my order was that it was more like 2mpg. If it's truly 5mpg less I'll wish I ordered the 3.21 diff.

No.

There are so many differences in the way people drive (city/highway/expressway, towing, aggressive/granny, etc.) Unless you drove the same truck (except the rear ratio), took the same route and drove the same way, you’ll never know the exact difference in mpg between the 3.21 and 3.92.

My sense from reading is that it’s 1-2 mpg at the most. Even at 2 mpg difference, you’re only looking at $200 or so more in fuel expense every 10,000 miles.

The option of the 3.92 rear on any package is one of the reasons I switched to a RAM from GMC. For me it is well worth the cost.

 

[Zeronet]

Here’s a proposed experiment for comparing 3.92 vs 3.21 for highway mpg...
The 3.92 gear in 8th gear is almost identical to the 3.21 in 7th gear. Load on the engine and rpm should be virtually the same. So anyone out there with a 3.21 truck could drive a predetermined highway route, at a set speed and note the mileage. Then run the same route, at the same set speed with the transmission limited to 7th gear (to simulate a 3.92).

It would be interesting to see the difference.