Fuel Efficiency vs Rear Axle Ratio

[Mr.Gigglez]

Let me know what you find out. My dealer is not very good at returning calls or customer service.

Will do !

 

[Mr.Gigglez]

I’ve learned to drive like a “ old man” to work and back .(44 miles) I’m getting 20-21. If I turn up the HK audio system and drive like a Jr in high school I get 12.9 with the 3.92 gears. It’s all about you . Hard tho with that Hemi not to have some fun. Gotta pay to play.

So being heavy on my pedal I get 12 and some change go light on it and it might move to 13.9/ 14.2 .... Its not all about you

 

[ExcursionDiesel]

So being heavy on my pedal I get 12 and some change go light on it and it might move to 13.9/ 14.2 .... Its not all about you

Reset your economy screen when you change driving styles unless you plan to Grandpa drive for 300 miles. The mpg calc in these trucks is a rolling average of the last several hundred miles and 50 miles of light footed driving won't change the average by much. I can get over 18 in the city in grandpa mode where I try to keep MDS on by feathering the throttle. I can also drive youthfully and get 12. Thats how a 7100 lb (edit: 6000 lbs, curb weight) 4x4 with 3.92, 11" wide tires, and a 1" factory lift is going to be. The EPA numbers are the result of professional drivers. I'm learning how to do the same for times when I'm not in a hurry.

 

[devildodge]

I have the 3.92 with 5.7 Etorque and if I drive it like I want to (more aggressive than average traffic) I get 12-13 City and 17.8 Highway. If I drive intentionally trying to keep the Eco light on, 17-18 City and 19-21 highway. 21 is at 60mph. 19 is at 70. 17.8 is at 78.

If I lived in flat country, I could get 24 cruising at 50 mph. Max economy seems to be around 1250 to 1400 rpm with the Eco light (MDS) on. MDS will not engage above 60 except downhill.

I have a fully optioned Limited 4x4 with Offroad Package. I keep it in Aero mode which I believe is still 1" above Aero on non-Offroad Package trucks. My truck weighs 7100 pounds.

I am not sure if you are implying you weighed your truck...but 7100 pounds is the GVWR...so if your truck weighs that much you need to take some stuff off of it.

Most limiteds have just at or under 1300lbs of payload...so your limited should weigh about 5800 lbs.

Not trying to be funny or smart...but will be interested to know what you meant.

 

[SpeedyV]

I am not sure if you are implying you weighed your truck...but 7100 pounds is the GVWR...so if your truck weighs that much you need to take some stuff off of it.

Most limiteds have just at or under 1300lbs of payload...so your limited should weigh about 5800 lbs.

Not trying to be funny or smart...but will be interested to know what you meant.

So...my truck supposedly weighs 6,031 lb (1,069 lb payload rating), making it as heavy as they come. Per my signature, I have the 3.92 rear end (and eTorque).

I flipped 1,800 miles today after putting 665 miles on the truck in the last couple of days. My last two tanks averaged 16.0 and 16.3 mpg with me taking it pretty easy, the last one being mostly highway miles at 72-75 mph. On an up-and-down hilly stretch from San Antonio to College Station, I averaged 17.5 mpg at 70-72 mph for about 100 miles...and then hit city traffic. Not too bad for a heavy truck with short gears, I think.

I found that up until about 72 mph, I can get MDS to kick in on flat stretches. Above that, it takes a slight downgrade or a bit of draft from a vehicle in front of me to see the Eco light.

 

[ExcursionDiesel]

I am not sure if you are implying you weighed your truck...but 7100 pounds is the GVWR...so if your truck weighs that much you need to take some stuff off of it.

Most limiteds have just at or under 1300lbs of payload...so your limited should weigh about 5800 lbs.

Not trying to be funny or smart...but will be interested to know what you meant.

I stand corrected. I meant the truck is heavy. 5800 lbs....7100 is fuly loaded. Bad gas mileage if you accelerate quickly. That's my experience driving mine.

 

[ExcursionDiesel]

So...my truck supposedly weighs 6,031 lb (1,069 lb payload rating), making it as heavy as they come. Per my signature, I have the 3.92 rear end (and eTorque).

I flipped 1,800 miles today after putting 665 miles on the truck in the last couple of days. My last two tanks averaged 16.0 and 16.3 mpg with me taking it pretty easy, the last one being mostly highway miles at 72-75 mph. On an up-and-down hilly stretch from San Antonio to College Station, I averaged 17.5 mpg at 70-72 mph for about 100 miles...and then hit city traffic. Not too bad for a heavy truck with short gears, I think.

I found that up until about 72 mph, I can get MDS to kick in on flat stretches. Above that, it takes a slight downgrade or a bit of draft from a vehicle in front of me to see the Eco light.

Our trucks should be about the same weight. I have every weight adding option available. I'm at 1800 miles and have nearly identical mpg as you on the interstate. MDS over 65 is a rarity on flat ground.

 

[SpeedyV]

Our trucks should be about the same weight. I have every weight adding option available. I'm at 1800 miles and have nearly identical mpg as you on the interstate. MDS over 65 is a rarity on flat ground.

Should be, as @Edwards also pointed out. For some reason, my Longhorn wins the ‘heaviest truck’ award with a payload rating that’s 72 lb lighter than a fully-loaded Limited. I’d love to know why.

 

[Dusty1948]

... FCA must have built in a fail safe to keep the truck in 8 cylinder mode until all eight pistons and cylinders are broken in? .

Actually, you are right. Not done intentionally. It's actually an emissions thing, but the effect is the same. You may have noticed earlier that the ECO lamp would illuminate only on steep downgrades.

Regards,
Dusty

2019 Ram 1500 Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, factory dual exhaust, 18” wheels. Now at: 005181 miles.

 

[Dusty1948]

I had decent fuel mileage from both of my 4 gens with the 3.92 axle, but I'm guessing you guys are much younger than me. The problem with a Hemi Ram with the 3.92 axle is they like to launch well and go through the gears briskly. This has a psychological affect on males with higher levels of testosterone, especially those that live in more urban environments.

Since most of my driving is in suburban or rural areas I selected my previous Rams (2019 & 2014) with the 3.92 axle based on the fact that most of my driving would be steady speed on county or state routes ( 35 - 55 MPH). I also had a towing requirement of over 9500 pounds. This generally worked well for me, but at steady interstate speeds of 65 MPH gas mileage took a nose dive.

Both of my 4th gens gave me 18+ around town with sedate driving. My 2014 had the 8-speed, and actually gave me better gas mileage on average. The 2014 was a rip, and I'm embarrassed to say that I succumbed to a few street challenges and was always the victor. But there's a price to pay, for sure. Drive a Ram with a 3.92 axle on the heavy side and you'll lose the advantage of those gears in low speed, stop and go driving.

Regards,
Dusty

2019 Ram 1500 Billet Silver Laramie Quad Cab 2WD, 5.7 Hemi, 8HP75, 3.21 axle, 33 gallon fuel tank, factory dual exhaust, 18” wheels. Now at: 005181 miles.

 

[Nebidok]

I have officially put 2 tanks through mine with the 3.21 and with no towing and probably 60%hwy and 40% city I have gotten 19.2 on the first tank and 19.1 on the second. I live in arkansas so pretty hilly here and weather in the 60's-70's.

 

[ExcursionDiesel]

I just crossed 2k on the odometer and am now noticing that ECO/MDS will stay engaged on mild grades and up to 65 on flat ground. I reset my economy screen and drove 40 miles at 65 mph with 6 miles in mild city driving. The EVIC indicated 22.6 mpg. It's improving as MDS stays on more.. I have 91 octane in the tank but had been running 89 before.

 

[Bwarren2]

3.92 rebel w Etorque and Im getting 14.5 City and 17-18 Hwy. Have less than 2K miles on it and I have a lead foot

 

[Edwards]

I just crossed 2k on the odometer and am now noticing that ECO/MDS will stay engaged on mild grades and up to 65 on flat ground. I reset my economy screen and drove 40 miles at 65 mph with 6 miles in mild city driving. The EVIC indicated 22.6 mpg. It's improving as MDS stays on more.. I have 91 octane in the tank but had been running 89 before.

After this road trip that put me over 2000 miles, I'm also noticing a big jump in how often and how long MDS stays active. Looking forward to the return trip to see if it does any better.

 

[Nöennig]

So being heavy on my pedal I get 12 and some change go light on it and it might move to 13.9/ 14.2 .... Its not all about you

That’s Unacceptable Mileage . I’d be hard pressed to not return that to the dealer. I’d heard a few horror stories before I purchased mine . I actually changed dealers after my initial Order so I could have a loaner if any problems like that popped up . Something is very wrong with your Ram. I had a F-150 Ecoboost Limited (22’ wheels as well )before my Ram and I can contest my 5.7 Hemi is as strong and gets much better mileage . I was always at 14-16 with the 3.5 . 6 years /80K . I Sincerely Hope you get to the bottom of this issue .

 

[19llhpb]

I have mentioned in other threads that I really don’t care about my mileage, gonna drive it anyway, however, I keep track just as a curiosity sake so we can compare. I have a fairly heavy truck (details in my signature). As I drive it everyday it weighs 6,300 pounds fully fueled. It has been weighed on a local truck scales. I run 87 octane and consistently get right at 16 mpg on paper with around 70% rural highway and county road driving and 30% in town. The terrain is flat here also. Have 6,300 miles on it.

 

[ExcursionDiesel]

That’s Unacceptable Mileage . I’d be hard pressed to not return that to the dealer. I’d heard a few horror stories before I purchased mine . I actually changed dealers after my initial Order so I could have a loaner if any problems like that popped up . Something is very wrong with your Ram. I had a F-150 Ecoboost Limited (22’ wheels as well )before my Ram and I can contest my 5.7 Hemi is as strong and gets much better mileage . I was always at 14-16 with the 3.5 . 6 years /80K . I Sincerely Hope you get to the bottom of this issue .

He said he drives heavy on the pedal. How's his mileage unacceptable Its easy to get 12 mpg in my truck if I stay on the gas. A 6200+ lb 4x4 driven hard is doing alot of work just moving itself quickly.