Hello,First time towing with 18 Navigator L 4x4 Ecoboost with 25k miles. We have a 34' camper that's 8k lb packed (7k on trailer axles, 1k on navi) using a weight distribution hitch. Got it dialed in to where the front is 1/4" higher with camper hooked up vs normal height. Drove from Illinois to Florida and back and averaged 5.8mpg (5.4 in mountains, 6.5 best mpg in flat states). Drove in normal drive mode with auto tow/hual mode, no cruise control, using paddle shift to keep best gear. Drove mostly in 9th gear, 7th or 8th up steepest hills. Drove around 75 mph. Anyone else pull heavy and see this bad mpg? We average 19 mpg around the Chicago suburbs. Wifes 15 Yukon XL towed this trailer on same trip multiple times at 9-10 mpg. Looking at this EcoBoost motor in other platforms show 10-12mpg towing. Spent $1,300 on fuel this trip! Help!

Try a trip 10 MPH slower. See how much the mileage improves.

75MPH is the problem. Try 55 to 60 and see how your mileage improves.

Slow down to no more than 60 mph.

Thanks for the advice to slow down and see if mpg improves. The V8 Yukon was 10 mpg at same speed. Do you think the issue is with v6 EcoBoost, the higher speed is causing more turbo boost to maintain speed and burning thru more fuel? Thanks for all the quick responses!

Short answer,,,,, Yes. The EcoBoost makes great power with a small package, fuel is the cost of that power.

2018 Navigator 6mpg when towing 8k lb camper Ecoboost

wanderingaimles
Explorer
May 20, 2019
Try a trip 10 MPH slower. See how much the mileage improves.
the_bear_II
Explorer
May 20, 2019
75MPH is the problem. Try 55 to 60 and see how your mileage improves.
bgum
Explorer
May 20, 2019
Slow down to no more than 60 mph.
FMF_Doc_B
Explorer
May 20, 2019
Thanks for the advice to slow down and see if mpg improves. The V8 Yukon was 10 mpg at same speed. Do you think the issue is with v6 EcoBoost, the higher speed is causing more turbo boost to maintain speed and burning thru more fuel?
Thanks for all the quick responses!
wanderingaimles
Explorer
May 21, 2019
Short answer,,,,, Yes.
The EcoBoost makes great power with a small package, fuel is the cost of that power.
Lwiddis
Explorer II
May 21, 2019
75 mph isn’t even legal in our state. Try 55 mph.

FYI https://learn.eartheasy.com/guides/fuel-efficient-driving/

“Increasing your highway cruising speed from 55mph (90km/h) to 75mph (120km/h) can raise fuel consumption as much as 20%.”

And you’re RVing.
dodge_guy
Explorer II
May 21, 2019
Sounds like 75 is killing your mileage. And ill bet that your loaded weight is far more than 8klbs loaded. I would say your going to be around 8500 lbs.

FWIW, when I had my V-10 Excursion and 35ft 9300 lb loaded TT I was averaging 7.5 towing at 72mph which is where the X liked it the best.
Jjsimon111
Explorer
May 21, 2019
Slow down also are you're tires on you're trailer ST's. They are rated at 65mph. Hate to see a blowout at 75 mph.
KD4UPL
Explorer
May 21, 2019
I think your mileage is on the low side for sure. I think the mileage you report from the Tahoe is on the high side. Is this actual calculated mileage or are you using the built in vehicle display?
I question your driving style first. You say you are shifting it yourself and not using cruise. I would think that putting the transmission in tow/haul and letting it shift itself might give you a bit better mileage. Also, I would think using cruise would improve it a bit too.
When I tow I general engage tow/haul and set the cruise. I let the vehicle figure it out.
As mentioned, make sure your tires are rated for that speed. If they are ST they probably aren't.
carringb
Explorer
May 21, 2019
FMF_Doc_B wrote:
The V8 Yukon was 10 mpg at same speed.!

Not possible. Maybe downhill with a strong tailwind. Unless you had the secret GM V8 that uses wormholes to shrink frontal area....