First extended trip with 5th wheel

[tim665214]

2016 Jayco Eagle HT 29.5 BHDS. Approx 10K GVWR. Tow vehicle is 2016 Ford F250 6.7 Diesel Crew Cab lariat. Coming from North of Fort Fort Worth to San Antonio via 281. For anyone not familiar with this route this is right on the edge of Texas Hill country. So not flat, but not exactly mountain terrain either. It was me, my wife, 15 year old daugther and her friend as passengers.

I was really hoping to get close to 12 mpg, but overall I averaged right at 10 mpg. Does this seem about right. I also noticed that when I had cruise control on (65 mph) that on the steepest hills it would always shift down to 5th gear, and 2 times it shifted to 4th. My truck had no problem holding speed, but it just surprised me that it had to shift down like that. When I wasn't using cruise control, it never had to shift into 4th, but it still shifted into 5th quite often.
Is this what everyone else is noticing who has a similar setup?

[laknox]

Allworth wrote:
With my combination (3500 long bed and 13K trailer) just under 60mph is my best tradeoff for time/mileage. Tor each 5mph faster than that I loose 1.5 mpg. Average over 40,000 miles.

This has been my experience in dropping from 65 to 60 mph; +1.5 mpg at 60.

Lyle

[laknox]

tim1970 wrote:
Does the fact that it was 102 outside when I was towing make a difference in the mpg?

Sure. The hotter it is, the higher the density altitude. Even with a turbo, you're still putting less air into the engine, so mileage won't be as good.

Lyle

[laknox]

RoyF wrote:
I rarely use cruise control when towing my fifth wheel -- too many downshifts. If it is just a slight up-and-down then I keep a steady throtle, let the speed drop on the uphill and build up on the downhill. My miles-per-gallon is better that way than when I try to keep constant speed up and down.

My dad has said for =decades= that he wished they made a cruise control that worked on RPM instead of MPH. You find that "sweet spot" based on RPM and take whatever speed you get.

Lyle

[Durb]

tim1970 wrote:
Does the fact that it was 102 outside when I was towing make a difference in the mpg?

Interesting question. I also wonder if it takes more energy to push a hole through air with high humidity than dry air. I know I have been towing on flat road with cruise control and hit a rain squall. The transmission down shifted to compensate for the rain. Banks Engineering always touts cool dense air for making power in a diesel. I imagine power would translate somehow to fuel economy.

[shadows4]

Wow!!! I feel much better about my old Ford 7.3L diesel and my 10.3 average on our recent trip. (see here).

[garyp4951]

RoyF wrote:
I rarely use cruise control when towing my fifth wheel -- too many downshifts. If it is just a slight up-and-down then I keep a steady throtle, let the speed drop on the uphill and build up on the downhill. My miles-per-gallon is better that way than when I try to keep constant speed up and down.

X2, and this is a lot better on the drive train.

[ChuckV1]

We also drive over the passes of 3500 to 5500 feet. I average 45 to 50 mph on most depending on how long they are, my fuel MPG with a 6.0 F350 DW CC 4x4 is right around 10.5 to 10mpg.

We have a 2017 Kz Durango Gold G384RLT at weighing in at about 13,500pds at the moment.

When all said and done I will probably average 10 mpg and I will be happy with that...

An old time truck driver told me if you want better fuel mileage drive up the hill and coast part way down the other side, he also stated then get a good run at the next hill so you want have to waste fuel pulling that next hill ... I have practiced this thought my over the road driving with semi's for 40 some years an always got a fuel bonus from the companies I drove for most every month ...

Safe travels

[Colo_Native]

I am on a trip right now in South Dakota from Colo. and I am getting about 10mpg see sig for what I am towing and I have a full water tank because I have no hook ups oh I might add never faster than 65mph

[Allworth]

With my combination (3500 long bed and 13K trailer) just under 60mph is my best tradeoff for time/mileage. Tor each 5mph faster than that I loose 1.5 mpg. Average over 40,000 miles.

[tim1970]

Does the fact that it was 102 outside when I was towing make a difference in the mpg?

[Cummins12V98]

With my Dually towing 10K and averaging 10 mpg I would be VERY disappointed!

[otrfun]

tim665214 wrote:
2016 Jayco Eagle HT 29.5 BHDS. Approx 10K GVWR. Tow vehicle is 2016 Ford F250 6.7 Diesel Crew Cab lariat. Coming from North of Fort Fort Worth to San Antonio via 281. For anyone not familiar with this route this is right on the edge of Texas Hill country. So not flat, but not exactly mountain terrain either. It was me, my wife, 15 year old daugther and her friend as passengers.

I was really hoping to get close to 12 mpg, but overall I averaged right at 10 mpg. Does this seem about right. I also noticed that when I had cruise control on (65 mph) that on the steepest hills it would always shift down to 5th gear, and 2 times it shifted to 4th. My truck had no problem holding speed, but it just surprised me that it had to shift down like that. When I wasn't using cruise control, it never had to shift into 4th, but it still shifted into 5th quite often.
Is this what everyone else is noticing who has a similar setup?

We've driven through the TX hill country a number of times. For those who haven't, the TX HC is comprised of many miles of repetitive, rolling hills. Depending on the truck and load a truck may downshift on nearly every hill. IMO, that's a lot of unnecessary wear, and tear on the tranny. We always lock out 6th, sometimes 5th, whatever it takes to keep the tranny from downshifting. Doing so may sacrifice MPG's slightly, but IMO a fair trade-off to prevent unnecessary wear and tear on the tranny.

We also turn off cruise control in the hills. The cruise control, in its all-out effort to maintain the exact speed, uses more fuel regulating the exact speed/power. When that fails it won't hesitate to force a downshift---using even more fuel. We get better MPG's with the cruise off. It's easy to prevent a potential downshift by simply rolling off the throttle slightly on a hill. You can make up for the slight loss in speed on the downhill side.

[RoyF]

I rarely use cruise control when towing my fifth wheel -- too many downshifts. If it is just a slight up-and-down then I keep a steady throtle, let the speed drop on the uphill and build up on the downhill. My miles-per-gallon is better that way than when I try to keep constant speed up and down.

[Dick_B]

In a recent post I noted that the force on the front of the RV increases as the `square' of the speed increase. So going slower means less drag and better mileage but probably not 20% better!