I'm sure you're right. The 3:55, rural driving at 55 mph I dare say from my experience with my "12', it wouldn't of even been in 6th gear some of the time. The "12" has the 6 speed.
I know the 8 speed with 3:55 wouldn't be in 8th under those conditions a lot of the time. My "rural" driving is a LOT of stop and go in town. I very often will be on 95 5-10 miles but it aint at no 55! LOL I'll run 70-80+!
I do like the feel of the 3:92's but the mileage right now is less than the 12 with 3:55. The differance in load on the engine is only starting from a stop, after that the tranny averages it out. Anyhow I like the truck and have no doubt it will make a differance in towing, although the "12" with 3:55 i locked in 5th and it towed great. Seems like about 2200 rpm at approx 70? Where maybe this one with 3:92 will shift to 8th at 70 or so but the end result will be about the same rpm. 390-395 hp is 390-395 hp. Neither will maintain 70mph at much less than 2200 or so rpm.
Is there a subtle body style change in 2015? It SEEMS to be a little more rounded and more aero than the "12"?

 

I've seen one picture of what was speculated as the 2015, and yes it was more rounded. The narrative with the picture suggested that the more aerodynamic style improved highway fuel mileage, even though the Ram is already has the least aerodynamic drag of any of the pickups.


On my 2010 with the 545RFE (5/6 speed) I found that it always got into 5th gear over 42 mph under light load. Of course, the transmission had learned my driving style, which is most often fairly gentle, and that, too, had the 3.92 differential.


The 8-speed in my 2014 will generally go into 8th above 45 mph. Unfortunately, the shifts above 3rd gear are so imperceptible that you can't tell unless you watch the tach. and then even that sometimes doesn't work for me. To verify the gear it's in I press the GEAR- button on the steering wheel and the current gear is displayed in the cluster. I've done this enough times to determine the pattern of speed versus load. It's also easier to stay in the ECO mode (MDS activated) with the eight speed that it was with the 5-speed in the '10.


Regards,
Dusty


2014 Ram Big Horn 1500 Quad Cab 2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 021214 miles.

 

The last ten tanks yielded the following fuel mileage (descending): 21.15, 19.54, 18.57, 19.63, 20.00, 18.36, 19.85, 19.40, 18.64, and 19.10.


These are hand calculated (not computer) readings. This represents the period between July 21st and today (1 Oct 2015). Almost all of my driving during this period was local, with about 15% expressway and the rest around town and rural roads. Average speed ranged between 27 and 32 MPH according to the computer. Average deviation between the computer and hand calculated fuel consumption was -3.61. Average fuel mileage was 19.42 MPG. Lifetime average is 19.01.


Comments.


In June I towed a 9200 pound tractor and trailer to my property 125 miles away in the Southerntier of western New York state. With my 2010 Ram, which was the basic truck as my 2014, except it had the 545RFE transmission (5/6 speed), towing the same tractor/trailer yielded me a 10.21 and a 10.67 for two trips with the truck in the Tow/Haul mode.


In June of this year I again towed the same except my 2014 has the 8HP70 (8-speed) transmission. This yielded me a 14.41 in the Tow/Haul mode.


I also discovered that the 2014 with the 8-speed transmission allows the vehicle to go into the ECO Mode when in Tow/Haul Mode. That was not the case with the 2010 and 545RFE.


Also in June, I recorded my highest gas mileage ever, 24.91 on a trip with an average speed of 48 MPH (state roads, many small towns).


Best regards,
Dusty


2014 Ram Big Horn 1500 Quad Cab2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 027554miles.

 

All ur posted mileages seem reasonable except,towing 9200 lbs and getting 14 plus mpg.

 

Dusty48,
What motor and rear combo do you have? Never mind I see it on a previous post.

 

In my 2010 Big Horn with the 545RFE transmission, selecting the Tow/Haul mode utilizes the 2nd prime gear in it's shift sequence (1st, 2nd, 2nd prime, 3rd, 4th) and prevents the transmission from going into 5th gear.


Apparently the 8HP70 in my 2014 will allow shifts all the way through to 8th gear when in Tow/Haul mode. The shift points are extended as they were with the 545RFE.


What I could not tell is whether I get torque converter lock-up in 8th on the 8HP70 when in Tow/Haul mode, although I'm suspecting it didn't.


Also, to clarify, my speeds average around 55MPH and never over 60.


Best regards,
Dusty

 

Year: 2015
Model: Ram 1500 Crew Cab Big Horn 20 inch rims
Transmission: 8 speed auto
Engine: 5.7L Hemi
Highway percent: 80
City percent: 20
Location: Ohio
Octane: 85
Hand or computer calc: Computer
Miles on truck: 5000
MPG: 22.2 highway / 15.5 city
Mods: Tonneau cover

 

2011 Ram 2500
6.7 cummins
6" lift/35s
5" turbo back exhaust
H&S mini maxx tuner
Getting 17-18mpg (50hwy/50city)
Once the EGR is completely deleted I expect the numbers to go up again

 

After scanning through most of the pages, my '09 1500 w/5.7L fits in with most.

I always use a calculator, as the dash read out only does the 'average' and is usually off.

Mostly town driving, I get 15-16, unless I'm playing with the HEMI power in the snow!

In Wisconsin, I average 19, best tank being 22.4

That's mostly expressway, and 55 MPH max.

In MN, on the freeway I get 15-16, as I'm running 70-75.

If I drop it down, mileage improves. Even running 65 vs 70 is a big increase.

Towing sucks her right down to 10-12.

Doesn't matter if it's the tractor on the 12K deck over, or the Kubota SXS on the small 6x10 trailer.

Our town is long, and sort of shaped like a 'T'.

30 miles from east to west, and 15 miles south to north.

The freeways also run in a 'T' pattern, so my city driving (around town driving) is a lot of getting on/off the freeway.

Plus Duluth is full of hills.

I'm happy with the truck, plenty of power, and the worst I get is 13MPG around town, and that is using the motor to get up to freeway speeds quick.

If I was to take all side streets, and stay off the freeways, I can jump the milage up to 16 around town.

But what fun is that??

 

Model:2014 Ram 1500 Quad Cab, 2WD
Engine: 5.7 Hemi
Trans: 8HP70 8-speed
Axle: 3.92 LSD
Current Mileage: 62984
Driving: Mixed, 70% rural, 10% city, 20% expressway


Last ten tanks, hand calculated: 18.87, 19.49, 19.83, 20.34, 20.17, 19.38, 18.95, 20.18, and 17.74 mpg.


Total tank fills: 174
Best tank avg.: 24.81 mpg
# of tanks over 18mpg: 105
# of tanks over 19mpg: 66
# of tanks over 20mpg: 38


Lifetime avg, hand calculated: 18.66
Average computer deviation from hand calculation: 3.12%


Compared to my previous 2010 with the same engine and axle ratio, this 2014 has a lifetime average 1.4 MPG better.


Regards,
Dusty


2014 Ram Big Horn 1500 Quad Cab2WD, 5.7 Hemi, 8HP70, 3.92 LSD, factory dual exhaust, 20” wheels. Now at: 061984miles.