2018 Navigator 6mpg when towing 8k lb camper Ecoboost

[FMF_Doc_B]

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!

[TXiceman]

Slow down. RV does not stand for race vehicle. Ir is a RECREATIONAL Vehicle.

75 is too fast for trailer towing. You tires may only be rated for 65 mph.

Ken

[BarabooBob]

I prefer to drive on US and state highways. If people get slowed down for more than 5 miles, I will pull over and let them pass. On the Interstates, there is room to pass. Unless someone has their head someplace it should not be, they should see that they are catching up to me and they can change lanes. That is why there is more than one lane. It is rare in the plains states to have an area where you can't change lanes to pass. The traffic is not heavy out there.

[kfp673]

Accept it is my recommendation. If you are like me, you will want to jump out of your skin doing a long haul like that at 55-60 mph. Personally, I think some of the most dangerous people on the roads are big trucks and people towing going too slow! When all the traffic is averaging 70mph and an RV is going 55mph it gets hairy! Maybe slow down to 70 but otherwise accept it as you and I both know you are not going to go slower just to save 1 mpg.

[aftermath]

Ecos are great engines, no question at this stage. They deliver great mileage when NOT towing but when you hook up, mileage goes down to where most of the rest of us are. They never claimed superior mileage when towing.

If you insist on towing at high speeds then go ahead and do that. Your mileage will suffer, that is established fact. Couple that with towing a long and heavy trailer with a flat surface pushing the wind will not help you out much. So about the only thing you can do to help is to slow down. Argue if you want but that is the fact you are facing.

[1320Fastback]

Those are some solid tests and numbers Bobbo. I also like either being passed or doing the passing but will never let someone tailgate or hang out along side my trailer or truck on the highway. It seems human nature to group together while driving but I simply don't trust any of them, humans that is! Lol

[Bobbo]

With both my previous RV and my current RV, I ran a test. On both of them I did a 500 mile trip at 60mph. Then I did a substantially similar 500 mile trip at 70mph. Increasing my speed by 17% caused a fuel usage increase of 33%. My Class C went from 9mpg to 6mpg. My TT went from 12mpg to 8mpg. All numbers rounded to the closest integer. My personal speed limit when towing the TT is 62mph. (Most people drive on a 5mph division. To avoid wolfpacks, I drive 2 or 3mph off of a 5mph division. Everyone who is not passing me is being passed by me. No one drives along with me.)

[1320Fastback]

Speed matters more than anything else because of wind resistance. Getting a rolling load moving obviously uses power but once it's moving it takes just a little power to keep it moving. We got a average of 13.68 over 6,000 miles earlier this year outside of California and 14.7 inside California because of the speed limit.

[Campingfarmer]

Round trip from Ky to Gulf Shores a few weeks ago had 8.5 mpg average and I kept it between 60 and 70. (mostly close to 60) Pulling a 7800# 32' trailer behind a 5.0 crew cab F150. I have done as bad as 7.0 average and as good as 9.5 depending on terrain and speed, but speed seems to have the largest effect.

[Groover]

1320Fastback wrote:
75mph is 23% less efficient than 55mph. THERE IS NOTHING YOU CAN DO ABOUT THAT.

40% better at 55mph is more realistic. Slowing down to 65 would probably get you up around 8mpg and letting the computer manage shifts is definitely worth a try.

[drsteve]

librty02 wrote:
I have 2 3.5 Ecos the 11 gets 10mpg towing through the mountains cruise set at 64. The 18 does the same routes at 10.5 mpg cruise set at 64. I have over 40k miles towing with the Ecos now and both get those averages consistently.

I never have nor will get the supposed NEED to tow so fast...part of Rving is enjoying the ride and scenery to the destination.

Yes I will avg 60mph on the 75 mph posted interstates...in 22 years of Rving NEVER had an issue...let those who aren't towing go around you it's very simple 😄

I am happy at 60-65 mph in the right lane with the trucks. No lane changing, passing, or getting annoyed at the semi going 67 mph in the left lane trying to pass one doing 65 mph. I arrive at my destination relaxed and ready to have a good time, rather than tense and frustrated.

[librty02]

I have 2 3.5 Ecos the 11 gets 10mpg towing through the mountains cruise set at 64. The 18 does the same routes at 10.5 mpg cruise set at 64. I have over 40k miles towing with the Ecos now and both get those averages consistently.

I never have nor will get the supposed NEED to tow so fast...part of Rving is enjoying the ride and scenery to the destination.

Yes I will avg 60mph on the 75 mph posted interstates...in 22 years of Rving NEVER had an issue...let those who aren't towing go around you it's very simple 😄

[mordecai81]

The sweet spot for my Eco F150 is 59-63mph. Over 20k towing TTs 5000-6500lbs I've averaged 10 mpg. If I go faster the truck doesn't feel as happy and the mpgs plummet so I budget our drive times accordingly. Doubling your speed quadruples drag. It's physics!

[dodge_guy]

My V-10 Excursion got its best mileage at 72. I tried 65 and it didn’t like it. At 72 I would average 7.5. At 65 I would average 7.3. Over 75 and it dropped to 6.9 or so. Crazy but that’s how it was.

[ajriding]

goducks10 wrote:
I always thought going faster would save gas. The sooner you get to where you're going the less time the motors running. 🙂

You are joking, but that is actually part of the math, a small part, but is one of the variables.

Part of variable is not the pure aerodynamics vs resistance, but with computer controlled injectors the truck will be programmed to feed fuel in at different rates depending on rpm or other variables. While the old carb engines would be predictable with increase in speed and decrease in mpg, the computer on modern trucks will interfere and make changes.

My diesel gets better mpg in the mountains and big hills than on flat. Maybe part is that I can coast downhill in N, or maybe that it is not much effort for truck to go uphill, but is way less effort to go back downhill, so net it less fuel needed.

My best ever mpg towing was I-70 in CO over the passes. I could keep boost low on climbs and just coast the downhill, or if I needed engine braking then would still not need fuel to go downhill.