Tow vehicle gas mileage

[Specsalot]

Interesting thread - Many here have deeper knowledge of what's in play from an engineering perspective. As an engineer, I'm glad they are taking it easy (little or no tech speak) on the rest of the posters.

My experience towing the same trailer (25' FC RBQ) with two different diesel TV's 13.4 - 14.4 MPG

Two TV's

2007 Jeep Grand Cherokee CRD (3.0L Mercedes Diesel) towing @60 MPH

2018 RAM 3500 6.7 CTD (dually 4WD 3.73 axle) towing @65-67 MPH.

Comment - I did not expect the RAM to match or best the Jeep's numbers. I upsized the TV because the Jeep wasn't really up to the task. I have not towed with the RAM @ 60 MPH, so I can't post an apples to apples comparison.

[Specsalot]

Originally Posted by gypsydad

The service manager at Ford dealer I service with here in North Austin, has the 7.3L on his F250. Told me he is sorry he got it due to mileage towing his 30' SOB and is selling for the diesel. Said he gets 8-9mpg towing and only around 14-15mpg when not towing... That said, I do wish I could get better mileage with my 6.7L. 12-13 towing is not great...neither is 15-16 around town...I have heard you can get a "kit" installed (Banks?) that will improve mileage to around 20 when not towing and also towing mpg. Another benefit is no DEF needed anymore? Anyone out there have this? If so, please share feedback and cost.

It will be interesting to see if anyone posts around this question. The shift to Urea/SCR (selective catalyst reduction) emission schemes has allowed engine designers to open up the combustion process. This has allowed compression ratio's to rise (which raises engine efficiency) while also boosting engine peak HP and torque. In 2019 Cummins/RAM had to completely redesign the engine block to handle the stresses, and redesign the front of the truck to accommodate a larger radiator to handle increased cooling needs. To make emissions, they had to shift to the Bosch CP 4.x fuel pump to increase fuel injection pressures. It's taken them 2 years to realize the move away from the CP 3.x was a bad decision. . . .

Given that the vehicle and engine designers don't always get things right, the challenge is finding tuners that can pull a rabbit out of the hat with nothing close to having a Cummins/RAM R&D budget. There is no free lunch.

[GettinAway]

Originally Posted by Specsalot

It will be interesting to see if anyone posts around this question. The shift to Urea/SCR (selective catalyst reduction) emission schemes has allowed engine designers to open up the combustion process. This has allowed compression ratio's to rise (which raises engine efficiency) while also boosting engine peak HP and torque. In 2019 Cummins/RAM had to completely redesign the engine block to handle the stresses, and redesign the front of the truck to accommodate a larger radiator to handle increased cooling needs. To make emissions, they had to shift to the Bosch CP 4.x fuel pump to increase fuel injection pressures. It's taken them 2 years to realize the move away from the CP 3.x was a bad decision. . . .

Given that the vehicle and engine designers don't always get things right, the challenge is finding tuners that can pull a rabbit out of the hat with nothing close to having a Cummins/RAM R&D budget. There is no free lunch.

I was actually starting to do a little math in my head. If I keep doing 12,000 towing miles a year, and I can go from 10 to 15 mpg. If diesel stays at about a 10% cost bump over regular unleaded, and I can get into a Ram 2500 Cummins for a $35,000 difference. How long would it take me to come out even? Then I factor in maintenance. That just screws up everything..

[brokeboater]

Originally Posted by GettinAway

How long would it take me to come out even?

63 years, seven months, 1 week, three days....

[twbucksr]

I’ve got the stats (fuel costs and miles driven) for my trip from Charlotte NC thru Fredericksburg tax and up to Pueblo, CO so I have the bank for the buck number.

I will post them this weekend.

GMC Sierra SLT with the Max Tow Package towing a 2018 27FBQ FC.

[gypsydad]

Originally Posted by GettinAway

I was actually starting to do a little math in my head. If I keep doing 12,000 towing miles a year, and I can go from 10 to 15 mpg. If diesel stays at about a 10% cost bump over regular unleaded, and I can get into a Ram 2500 Cummins for a $35,000 difference. How long would it take me to come out even? Then I factor in maintenance. That just screws up everything..

Yea, that is a concern for some. I just tell you, the difference in "towing" with the diesel on larger AS's is night and day with the diesel...hard to accept, I know, until you have actually towed with a diesel with engine brake engaged...to me, thats why we made the investment...now 114K miles in 3 years; 50K on the AS...no complaints and no issues...(other than fuel prices in CA and oil change costs and parking)

Oh, and of course more payload!

[GettinAway]

There’s no doubt in my mind that towing would be easier with a big diesel, but like so many things in life it comes with a cost. We put the money into the trailer instead of the truck. Obviously, if I thought I was putting others at risk I would change trucks. At this point, with the modifications done to the truck, I’m more worried about frame separation from my rear bike rack, than trailer control issues. I do also wish I got 15 mpg towing, but I’d also like my next birthday to be my 27th instead of my 67th.

[Specsalot]

I hope someone has the audacity to comment that there is nothing rational about camping. Oops - I guess I just did

Smiles per mile > bang for the buck. Understanding bang/buck still represents good decision-making fodder.

Running an engine at peak torque is generally way more efficient than running at / near peak horsepower. All the builders know how to do this math very well. In order to market to the largest audience, they are pretty cagey about how much info they put on paper. TFL Trucks (Youtube) is a good source of real world information that seems to be accurate.