Towing MPG Comparison

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.

lone_star_dsl

Well-known member
Joined
Sep 4, 2009
Posts
828
Location
Monument, CO
My friend and I each towed our trailers from Grand Island, NE to Wichita Falls, TX the other day. I figured it would be a great performance and MPG comparison.

We both have extremely similar trucks. 2016 Ram 3500 dually, crew cabs. His truck has 3.73 gears and mine has 4.10's. Other than that (and the color) they are identical.

His trailer is a 2006 New Vision Sportster by KZ and mine is a KZ Sportsman. Both have identical front caps but mine is a few feet longer and is a triple axles, his has tandems.

We each set our cruise at 72 mph and headed south with a minor tail wind. Roughly 570 miles later, we pull into our destination with my truck averaging 9.2 mpg and his averaging 8.1 mpg.

This confirms my findings from a few years ago when I switched trucks and went from 3.73 gears to 4.10's. Just goes to show that keeping an engine in it's ideal powerband is more important than focusing on low RPM cruising.
 

Scott 3

Well-known member
Joined
Jan 17, 2016
Posts
664
Good timing on your post.  I will be ordering a 2500 in a couple of weeks with the 4.10s.  I'm a little concerned about it being a daily driver.  I've read other posts that suggest what you posted. 
 

Gary RV_Wizard

Site Team
Joined
Feb 2, 2005
Posts
76,166
Location
West Palm Beach, FL
Good data, but I don't think a conclusion of "4.10 is better" would be accurate  As lone star says, "keeping an engine in it's ideal powerband is more important than focusing on low RPM cruising".  For a given speed, trailer, tire drag (size & number), wind resistance, etc., one rear axle gearing will be more optimal than another. Whether a particular rig works better with 3.73, 4.10, 4.33 etc, is much harder to judge in advance.
Basically the engine will perform most efficiently when it is at or near its peak horsepower rpm. A popular rule of thumb is to stay between the peak HP and peak torque rpms.  Modern automatic transmissions are programmed to do that in conjunction with the engine computer.  Maximum fuel economy is near always achieved by keeping the transmission in its top gear  at an engine rpm that will keep it there without frequent shifting.  Not the lowest rpm possible, but the lowest one that meets the criteria stated.  That may mean a lower or higher road speed (mph) than you prefer. If a given speed is more important than max mpg, then optimize for that and accept whatever mpg it yields.
As the data shows, a higher ratio rear axle may not be lower in fuel economy if the rest of the paremeters allow for a better overall powertrain gearing. 
 

lone_star_dsl

Well-known member
Joined
Sep 4, 2009
Posts
828
Location
Monument, CO
OBX said:
Good timing on your post.  I will be ordering a 2500 in a couple of weeks with the 4.10s.  I'm a little concerned about it being a daily driver.  I've read other posts that suggest what you posted.

Are the 3.42's still available? In my opinion, they would be the better choice for a daily driver that tows secondarily. Trucks equipped with those gears are getting really good fuel mileage empty and the option of towing in 5th gear should have the engine near it's peak hp and tq.
 

lone_star_dsl

Well-known member
Joined
Sep 4, 2009
Posts
828
Location
Monument, CO
Gary RV_Wizard said:
Good data, but I don't think a conclusion of "4.10 is better" would be accurate  As lone star says, "keeping an engine in it's ideal powerband is more important than focusing on low RPM cruising".  For a given speed, trailer, tire drag (size & number), wind resistance, etc., one rear axle gearing will be more optimal than another. Whether a particular rig works better with 3.73, 4.10, 4.33 etc, is much harder to judge in advance.
Basically the engine will perform most efficiently when it is at or near its peak horsepower rpm. A popular rule of thumb is to stay between the peak HP and peak torque rpms.  Modern automatic transmissions are programmed to do that in conjunction with the engine computer.  Maximum fuel economy is near always achieved by keeping the transmission in its top gear  at an engine rpm that will keep it there without frequent shifting.  Not the lowest rpm possible, but the lowest one that meets the criteria stated.  That may mean a lower or higher road speed (mph) than you prefer. If a given speed is more important than max mpg, then optimize for that and accept whatever mpg it yields.
As the data shows, a higher ratio rear axle may not be lower in fuel economy if the rest of the paremeters allow for a better overall powertrain gearing.

A big piece of it that I should have focused on is road speed. My truck hates towing at 65 mph. It likes to go back and forth between 5th and 6th quite often. At 70+ mph, it's extremely happy...and so am I.

With trucks now being equipped with 8 and 10 speed automatics, matching the proper gear to engine efficiency and/or power requirements and road speed becomes much easier.
 

Lowell

Well-known member
Joined
Aug 15, 2005
Posts
2,221
Location
Tempe, AZ
While this is interesting, I don't think it is conclusive.  I think you could get that much variation between two identical trucks. And it doesn't take into consideration variation between the trailers being towed, their wind resistance, drag, etc.  Would be good to switch trailers being towed and see if difference diminishes or increases.
 

lynnmor

Well-known member
Joined
May 14, 2013
Posts
1,586
Lowell said:
I think you could get that much variation between two identical trucks. And it doesn't take into consideration variation between the trailers being towed, their wind resistance, drag, etc.  Would be good to switch trailers being towed and see if difference diminishes or increases.

I agree with that, my bet is that there was considerable difference in drag.  The front caps are only a portion of the equation.

Those that don't like the transmission shifting, and want a 10 speed transmission, better learn to like shifting.
 

steveblonde

Well-known member
Joined
Jan 8, 2015
Posts
4,421
Location
calgary alberta
My Ford dually With 3.55 gears gets alot better mileage than both my buddies Chevy dually with 3.73 gears and my Chevy SRW 3500 with 3.73 gears the Ford with 4.10 gets horrible mileage.

Cant comment on the Ram but its an inline  6 oppossed to the V8 diesels
 

longhaul

Well-known member
Joined
Dec 21, 2008
Posts
562
We each set our cruise at 72 mph and headed south with a minor tail wind. Roughly 570 miles later, we pull into our destination with my truck averaging 9.2 mpg and his averaging 8.1 mpg.
Probably good results but I wouldn't  base any hard mpg figures base on a single tank filled by two different persons. I would rather look at a mpg average based over 3-5 tanks all with pencil figures...filled with the same pump and stop filling after the 2nd click.
 

rbrdriver

Well-known member
Joined
May 23, 2016
Posts
327
Location
Visalia, CA
I have the 2017 Ram 3500 Dually with the Aisin tranny and 4.10 rears towing a 42' Alpine fiver and so far we average around 10 towing at 65 m.p.h. Just thought I would throw in my 2 cents worth...?..
 

kdbgoat

Well-known member
Joined
Apr 16, 2014
Posts
6,329
I lurk on a couple of Ram forums when I get bored, and there's a few that are completely happy with their 3:73's, but most like their 4:10's better. There's some with the 3:73's that wish they had got 4:10' instead, but haven't read any 4:10 owners that wished they had 3:73's. There's a couple that have 3:42's and though they admit a slower take-off, they don't mind them. They just run one gear lower than the 4:10 guys.
 

Lou Schneider

Site Team
Joined
Mar 14, 2005
Posts
11,794
I have a 1999 Ford F350 that I'm pretty happy with.  2WD single rear wheel crewcab with the 7.3 Powerstroke, automatic and 3.73 rear end and tows a 29 ft. Sunnybrook bumper pull.  All sorts of reserve capacity on both payload and trailer weight.

The truck has a cab height camper shell on it's 6 ft. bed and the trailer is lower than a 5th wheel so the aerodynamics are pretty good.  Highway running is in overdrive with occasional downshifts to third gear on hills.  I've only had to grab second gear a couple of times in places like Wolf Creek Pass.

I regularly get 12 mpg towing at my preferred cruising speed of 65 mph, in overdrive the engine runs around 1800 rpm, slightly above it's 1600 rpm torque peak.  Solo the truck gets around 18 mpg and rides stiff but decent.
 
Top Bottom