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Old 07-28-2020, 04:06 PM   #1
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Almost 10 MPG...

We usually get high 7's. Maybe 8's if I drive and take it easy. But this last week it was just my son and I out for seven days with no agenda!


Nothing that had to be done, no place we had to be. Since we had nothing to rush to, I kept it at 60mph on I-80 for most of the day. I gassed up twice and both times my math showed we were in the high 9's, almost 10, MPG.


Wowser.


Usually I'm at 65 and will put a bit of a foot in it to get up a hill.
But, I'm just flabbergasted at the improvement. Just 5 MPH less.
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Old 07-28-2020, 04:26 PM   #2
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Originally Posted by pconroy View Post
We usually get high 7's. Maybe 8's if I drive and take it easy. But this last week it was just my son and I out for seven days with no agenda!


Nothing that had to be done, no place we had to be. Since we had nothing to rush to, I kept it at 60mph on I-80 for most of the day. I gassed up twice and both times my math showed we were in the high 9's, almost 10, MPG.


Wowser.


Usually I'm at 65 and will put a bit of a foot in it to get up a hill.
But, I'm just flabbergasted at the improvement. Just 5 MPH less.
Not surprised since wind resistance is the "enemy" and it increases exponentially the faster you go.

Right from the web:

Does wind resistance increase with speed?

The increase in speed leads to an increase in the amount of air resistance. Eventually, the force of air resistance becomes large enough to balances the force of gravity. At this instant in time, the net force is 0 Newton; the object will stop accelerating. The object is said to have reached a terminal velocity.
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Old 07-29-2020, 11:23 AM   #3
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So if I go 0.0mph, I'll get infinite MPG?



Or is it more of a Zeno's Paradox thing?


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Old 07-29-2020, 12:54 PM   #4
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You must of had a good tail wind. My MPG will go up almost 2 mpg with a good one. Too bad it works just the opposite when hitting a good head wind. Generally its about 7.5 MPG
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Old 07-29-2020, 12:58 PM   #5
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I tend to get around 10.1 to 10.3 overall. After having some fuel issues in Colorado I went with Shell or other name brand premium for the next 1,300 miles and averaged 10.5 to 10.7 on each fill. I was a little surprised.
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Old 07-29-2020, 01:53 PM   #6
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So if I go 0.0mph, I'll get infinite MPG?

How about down long hills?
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Old 07-29-2020, 03:44 PM   #7
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Mpg

Quote:
Originally Posted by pconroy View Post
We usually get high 7's. Maybe 8's if I drive and take it easy. But this last week it was just my son and I out for seven days with no agenda!


Nothing that had to be done, no place we had to be. Since we had nothing to rush to, I kept it at 60mph on I-80 for most of the day. I gassed up twice and both times my math showed we were in the high 9's, almost 10, MPG.

Wowser.

Usually I'm at 65 and will put a bit of a foot in it to get up a hill.
But, I'm just flabbergasted at the improvement. Just 5 MPH less.

My first guess would be tail wind and relevant wind resistance, especially if you're on the open highway. You may find that a given speed, along with your engine & transmission, you'll find that "sweet spot". My truck seems to like to tow between 60-65 MPH.



You could look at other variables like total weight. Less weight = less energy needed to move it. Or possibly you got a tank full of gas that's got less ethanol in it. Gas companies like to add upwards of 10% ethanol in their fuel to get more money out of us and I think everyone's aware that ethanol is cheaper than gas but provides 30% less power per gallon.



My obvious suggestions would be:
* Use gasoline with the least amount of ethanol in it (if possible)
* Keep your rig as light as possible. Don't haul around extra stuff if not needed, keep tanks empty or minimal fresh water for road emergencies.
** Water weighs 8lbs per gallon. So that 50 gallon fresh water tank will add an extra 400 lbs if you fill up.
* Use your cruise control to keep the speed constant (don't use in really hilly areas).
* Wash/Wax your rig and then slap a "TURBO" sticker on it for maximum performance!! LOL
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Old 07-29-2020, 08:09 PM   #8
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My first guess would be tail wind and relevant wind resistance, especially if you're on the open highway. You may find that a given speed, along with your engine & transmission, you'll find that "sweet spot". My truck seems to like to tow between 60-65 MPH.



You could look at other variables like total weight. Less weight = less energy needed to move it. Or possibly you got a tank full of gas that's got less ethanol in it. Gas companies like to add upwards of 10% ethanol in their fuel to get more money out of us and I think everyone's aware that ethanol is cheaper than gas but provides 30% less power per gallon.



My obvious suggestions would be:
* Use gasoline with the least amount of ethanol in it (if possible)
* Keep your rig as light as possible. Don't haul around extra stuff if not needed, keep tanks empty or minimal fresh water for road emergencies.
** Water weighs 8lbs per gallon. So that 50 gallon fresh water tank will add an extra 400 lbs if you fill up.
* Use your cruise control to keep the speed constant (don't use in really hilly areas).
* Wash/Wax your rig and then slap a "TURBO" sticker on it for maximum performance!! LOL

Although I love your assessment, especially about ethanol, I have never experienced more than 5-8% improvement of mpg when using non ethanol gas regardless of driving conditions. Driving speed and wind are the only significant variables in mpg as far as I am concerned. I will continue to purchase non ethanol gas out of principle but I have yet to see a significant improvement of mpg and nowhere near 30% for sure. Also in my experience weight has had no effect at all on mpg which blows me away. I am convinced that wind resistance is the enemy.
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Old 07-30-2020, 11:29 AM   #9
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Shoot, I get 10MPG in my 2018 Ram without any towing being done.
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Old 07-30-2020, 01:11 PM   #10
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I'm gunna test this my next trip

It's up hill a lot,but gunna try to keep my FOOT out of it and see if mine increase

I'm usually right around 7mpg
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Old 08-02-2020, 11:00 AM   #11
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It looks like this is a gas mpg thread. What are the Jayco diesel seneca users getting. I got 8.6 mpg on my first tow. Cruise set mostly at 64.
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Old 08-02-2020, 07:59 PM   #12
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I have a Jayco 31 DS...Typically I get 7.5ish MPG. Pulled my toad for the first time..flat ground no mountains...tou know, Jersey where the highest montain is an off ramp...some stop and go traffic for about 45 mins...and got 6.3 Mpg. This fall we'll be heading for Arizona..Tempe...I'll post the MPG from that trip then.

Delaware water gap with the grand kids is next.

The guy who installed our towing package said the toad shouldn't effect the MPG to much because the RV box does all the wind busting....He said flat towing doesn't put any weight on the rear axel of the RV...and once you get going the toad doesn't really make any difference. Should I believe him?

I flat tow a 2019 Ford Edge ST. Choose it because it has a nice back seat area and room in the back for chairs and a cooler. Oh, it also has 347 HP. Tricked the wife into a race car.
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Old 08-02-2020, 08:59 PM   #13
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And I thought I was getting bad MPG, sounds like you guys really suck, no pun intended. Lol!
2015 3500 Silverado crew long bed dually Duramax pulling a 2017 Northpoint 375, 44' long and stands 13'-3" stick measured when coupled to the truck. The way the DW packs the trailer is between 15 and 16k. I keep the fun pedal set to 72mph and can get right at 10mpg. Fairly decent headwind I'm in the low 9's. I have a buddy with a 2500 pulling a Cedar Creek that gets about 1 - 1.5 mpg better than me. Same height trailer, a little shorter, and weight wise is a little lighter. I have another buddy with a 2500 and he gets better MPG than me even empty. All three trucks have the same rear diff and gearing, same transmission, same Duramax engine. The 2500's are both 16's and my dually is a 15. Engines are the same HP and everything between 15 and 16. All 3 of us even ran the same fuel. About the only thing we can come up with is my truck is a little heavier but we think the biggest thing is the extra set of tires on the back end is more rolling resistance and because its wider in the rear the dually part sticks out more making it less aerodynamic than his. I keep my tires on the truck and trailer at max psi too.
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Old 08-03-2020, 12:08 AM   #14
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It looks like this is a gas mpg thread. What are the Jayco diesel seneca users getting. I got 8.6 mpg on my first tow. Cruise set mostly at 64.
Just returned to AZ from SoCal on the I-8 today. 110+ heat and hills towing in the Seneca. Scan Gauge shows 8.4 MPG. Trip out was 9.5.

Last few trips have been from AZ to SoCal on the I-8 towing our ‘17 Grand Cherokee. I’m about 27,500 Lbs with three pax and stuff, 1/3 water and full fuel. I typically see 8.5 - 9.5 MPG on this run, depending on speeds, winds, and temps. I usually cruise at 63-65 in AZ and 60 in CA. Long 6% grades with plenty of WOT running going into the area and same coming home though lots of coasting down hill.

I’m getting better at keeping the engine near peak torque and taking whatever speed I get until revs drop enough to require a downshift. The slowest I have seen is 45 MPH with above weights going up the LONG 6%er after Ocotillo heading West on the 8 - that’s about 10 miles of hard running in high heat.
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Old 08-03-2020, 06:22 AM   #15
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I have a Jayco 28rls being towed with a 2017 F350 6.7 diesel. I get 12mpg. My last tow vehicle was a 2015 F150 with a 3.5 and I got 9mpg.
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Old 08-05-2020, 07:02 AM   #16
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Hard to keep it at 60

I usually get around 9 mpg if I keep it under 70 and not towing the wrangler. Usually interstate driving in the northeast mountains. I calculated the same 9 mpg towing a cx5 to Florida on flat 95 south. 1 to 2 mpg loss towing is my guess.
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Old 08-05-2020, 12:47 PM   #17
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65 Suits me Fine

65 mph feels normal, even next to the car transport semi, when I drive at 65 mph. Given that, last months trip to MI resulted in 10.9 mpg. TV is 2015 RAM, 5.7L, CrewCab, short bed, 3.21 Axel. Our GCW was 12,500 with full tank of fuel, 2 passengers, minimal cargo and minimal TT cargo. 1,300 below Max GCWR. Thats about the most I like to handle.
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Old 08-05-2020, 01:30 PM   #18
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Presently traveling coast to coast, half way and with non ethanol consistently getting 9.6 mpg with a Redhawk 26 xd
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Old 08-05-2020, 03:44 PM   #19
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We've put over 70,000 miles on two Class C's since I retired. Los Angeles to Ohio to Key West (6 times) to Nova Scotia to Ohio to Texas to Maryland to Florida to Alaska to Ohio ...

What is the "tailwind" you speak of? We've never encountered one.
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Old 08-05-2020, 04:43 PM   #20
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That's what Bonneville land speed records are all about, if there was no increase in wind resistance the speeds would be out of the world.
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