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MPG at 80 MPH

bvigne01

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^^ about the same numbers I get, 3.21s 4x4 limited with oem 22s.
I Have the 3.21 in a Longhorn with factory 20 wheels and tires. Today I gut just under 20 MPG to and from work in the Dallas area. Kind of disappointing and I wish I would have got the 3.92. If the ground was flatter I think i would get better mileage. We have enough incline to cause downshifts and its hurting me. Truck is new so I hope it gets better
 

J-Cooz

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What is your normal cruising speed on the highway?
About 112kmh (70mph). Seeing around 28-30 consistantly on the highway. Loving the EcoDiesel so far. My Hemi struggled to get 19 at the same speeds and was constantly downshifting up small hills and rarely ever stayed in Eco mode. It was also a 3.92.
 

StuartV

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About 112kmh (70mph). Seeing around 28-30 consistantly on the highway. Loving the EcoDiesel so far. My Hemi struggled to get 19 at the same speeds and was constantly downshifting up small hills and rarely ever stayed in Eco mode. It was also a 3.92.

I have a Hemi with the 3.92. That is about the same as what I get at that speed. I.e. struggle to get 19 if I'm cruising at 70. Struggle and generally fail.

But, I pretty much never cruise at 70, either. If I'm on the road, that means Interstate and cruise set at 80. Mileage really drops off the more you exceed 70. I get about 17 when cruise is set at 80. That is hand calculated using the Fuelly app at every fill-up. The onboard lie-o-meter ALWAYS says I got better than I really did. My last two highway-only runs were:

Actual 17.4MPG, computer said 18.5.

Actual 17.2MPG, computer said 18.2.
 

J-Cooz

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I have a Hemi with the 3.92. That is about the same as what I get at that speed. I.e. struggle to get 19 if I'm cruising at 70. Struggle and generally fail.

But, I pretty much never cruise at 70, either. If I'm on the road, that means Interstate and cruise set at 80. Mileage really drops off the more you exceed 70. I get about 17 when cruise is set at 80. That is hand calculated using the Fuelly app at every fill-up. The onboard lie-o-meter ALWAYS says I got better than I really did. My last two highway-only runs were:

Actual 17.4MPG, computer said 18.5.

Actual 17.2MPG, computer said 18.2.

Speed limits in Ontario Canada are pretty lame. Most are 100kmh (62mph) and only a few highways are 110kmh. It helps the fuel economy for sure.

The dissapointing Hemi mileage was why I got rid of it. The diesel just seems to effortlessly cruise on the highway in 8th gear, doesn't downshift, and just chugs along. Even going up hills it'll be getting 20mpg under load.
 

J-Cooz

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I'm kicking myself for not getting the 3.92 thinking i would get better mileage with the 3.21. Its not really turning out that way in the real world
It's been beat to death on here, but I think if you drive reasonable speeds the 3.92 can be just as good as the 3.21 because you aren't lugging the engine as much. At higher speeds I'm sure the 3.21 has a bit of an advantage.

I drive with a pretty light foot and tend to get better mileage than most and I do almost exclusively highway driving.

Either way I think the EcoDiesel is awesome and am very happy with my switch from the Hemi.
 

SilverSurfer15

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The 3.21 trucks drive a lot nicer IMO. It’s hard to lug the 3.92 down and the rpm always seem a bit high. But I only went about 15 miles on the test drive so maybe it’s all in my mind.
 

SpeedyV

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The 3.21 trucks drive a lot nicer IMO. It’s hard to lug the 3.92 down and the rpm always seem a bit high. But I only went about 15 miles on the test drive so maybe it’s all in my mind.
You’re probably not wrong on the “lugging”, although I’d bet the 8-speed sort of negates any real-world distance at any speeds except off the line or at 70+ mph. And if I’m wrong, that’s okay...the HEMI isn’t a low-end engine ;)
 

Aseras

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The real issue with the 3.92 and other trucks is stock is that FCA nerfed the throttle response curse SO BAD. 2/3 of the pedal is dead.

A pedal commander while only remapping the throttle response REALLY made my truck driveable. I'm completely amazed at how much of a difference it makes. Coming from a PHEV that had a sport mode that did similar thrings with the throttle mapping and suspension when set to sport mode, it was easier for me to accept and not just attribute the anemic feeling my truck had overall to turbo lag. It is practically gone with the pedal commander.

FWIW the 3.21 should give you better highway mileage. the 3.92 is geared more for towing, so the 8th gear is shorter giving more torque and a higher rpm at highway speed. the 3.21 should be about 20% better. the rest of the transmission 2nd through 7th are the same. 7th is 3.92 on the 3.21 and 8th is 3.21. the 3.92 has a lower 1st gear, then its all the same as the 3.21. the 3.92 is marginally quicker due to shorter gears. but its fractions of a second.

for me, the pedal commander took my truck from going 0-60 in about 7-9 seconds to a sub 5 second if I can keep traction control from kicking in spinning the 285r22 tires. A stab of the gas in town and I can usually chirp the tires in 2wd. before it was just a delay and slow response. going up an onramp to 70mph no longe feels like a slog, the truck is happily going 70mph even pulling 4,000lbs as fast as I need it to.

This nannying BS is going to get people killed. The throttle should be responsive and predictable not a mush pile of lag to meet some BS emissions mark so some chukclefark at FCA can get a bonus. Same with the IBS Shenanigans.
 

SilverSurfer15

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Yea the throttle is weird for sure, people keep saying it’s turbo lag but That’s not the case. I’ve never wanted to run a pedal commander but I’m interested for this. I also want a full tune, and who knows when that will happen, so I might have to try it.
 

StuartV

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Yea the throttle is weird for sure, people keep saying it’s turbo lag but That’s not the case. I’ve never wanted to run a pedal commander but I’m interested for this. I also want a full tune, and who knows when that will happen, so I might have to try it.

I posted a little while back after having a FB messenger chat with Green Diesel Engineering. They are working on a tune for the new ED, but they said it would be about 18 months.

Personally, I am keeping my '19 for maybe 3 years and then plan to trade it in for an ED. I.e. basically wait for a tune to be available and also give it a couple of years in the real world to get any kinks sorted out. Then get one. With a 3.21. 2200 RPMs at (my) highway speeds is for the birds.
 

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