fuel economy

Discussion in 'Tow Vehicles, Hitch & Towing' started by JT1, Oct 6, 2021.

  1. JT1

    JT1 New Member

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    Hello, we are considering purchasing a pup, and wondering what percentage does towing a pup affect your fuel economy. Thanks.
     
  2. Sjm9911

    Sjm9911 Well-Known Member

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    A lot.
     
  3. Raycfe

    Raycfe Waterford Ct.

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    Fuel mileage depends on so many things. Keep your speed at 65 mph max. A remand guess would be about 30% mileage drop.
     
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  4. NMroamer

    NMroamer Well-Known Member

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    There are so many variables involved in fuel economy that it should only be a checked out of curosity.
     
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  5. Arruba

    Arruba Well-Known Member Gold Supporting Member

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    As mentioned, it depends on a lot. Based on my stuff, using my 7.3 liter Diesel to tow equals 0.0% loss regardless. Using either my old V8 Expedition or my V6 Explorer is a 20 to 30% loss in fuel economy; conditions, terrain, and speed dependent.

    Good luck with your decision.
     
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  6. generok

    generok Well-Known Member Gold Supporting Member

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    It does go down, for sure. It's kind of the price of doing business. I saw about 20% drop, maybe, but then became indifferent to it.
     
  7. Sjm9911

    Sjm9911 Well-Known Member

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    Ok, so i was playing around a bit. It depends on what your tow vehical is and what your pulling. It can be 0 mpg or 35 mpg. My new truck suffers no impact on the mpg. But its a hog anyway. And thats with a TT. Lol.
     
  8. PopUpSteve

    PopUpSteve Administrator

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    I find I loose about 1 mile per gallon on the open road.
     
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  9. BikeNFish

    BikeNFish Well-Known Member

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    With my RAM, I lose about three miles per gallon when towing, I lose five miles to gallon when bucking a headwind, I lose two miles per gallon when I have a stiff tailwind. Something just doesn't seem fair about that. This all at 65mph.
     
  10. bluespruce

    bluespruce Member

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    Our last trip was about 4000 miles but only about 3000 of that was pulling the trailer. I saw about a 15-20% decline in mileage while towing. But we were hauling pretty good (70mph) across the Great Plains. On days with 2 lane roads and lower speeds there was less of a difference. And the day with a wicked headwind I thought I had a hole in my gas tankā€¦

    I figure I pay a little more in gas but way less in lodging. And I sleep in my own bed. And I can have a campfire and smell the morning air in a campground. Plus see the stars at night and hear the coyotes howl. Well worth the price of gas for our family.
     
  11. MNTCamper

    MNTCamper Well-Known Member

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    I get about 22-23 mpg with my minivan for highway travel without the camper. Towing the camper, I get 16.5 to 18 mpg. I tow at 71 mph as we often take longer trips and put on a lot of miles. There are not issues towing at all, we just took a trip about 330 miles away and the camper towed like a dream, hardley even knew it was back there.
     
  12. WrkrBee

    WrkrBee Un-Supported Member

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    I never check the mileage. The Expedition dragging a big brick up and down hills loves to be fed a lot. When it gets to half a tank and I see a station, I fill up.
     
  13. firepit

    firepit Well-Known Member

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    Pulling is Pulling...Fill tank as needed
     
  14. Snow

    Snow Well-Known Member

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    Fuel economy and towing anything other then a bicycle rack are two things that don't go together.. You want to improve towing mileage, get a vehicle with a bigger engine and transmission, that would downshift less climbing hills or passing. Keep speed at or below 65mph .
     
  15. davido

    davido Well-Known Member

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    In my (no longer mine) 2015 Ford Explorer Sport we would go from 19.5 MPG down to about 14.5 MPG. So that's a 5MPG difference. It makes sense; this is a relatively lightweight vehicle with a 350HP twin turbo ecoboost engine in it. It's designed to not use a lot of fuel for normal day to day use, and to have lots of room to suck down fuel when needed.
    On my 1995 Ford Bronco 5.8L XLT I go from 15 MPG to 12.7 MPG

    Those are the two that I've used recently enough to remember.

    The factors include weight, speed, and frontal surface area. Weight is mostly a factor for climbing hills.

    An object in motion wants to remain in motion if there are no forces trying to thwart that. So if you take aerodynamics and bearing / tire friction / rolling resistance out of the equation, a trailer travelling on a flat road at 70mph will continue to do so as long as there is road ahead, with no additional energy required to maintain the speed. But tire friction, rolling resistance, and aerodynamics are part of the equation. Aerodynamic force is a function of the square of velocity. So when you double speed, you quadruple the aerodynamic drag. Travelling at 70mph has four times more aerodynamic drag than travelling at 35 MPH. At very low speeds, factors such as tire pressure, tread pattern, and bearing friction are a larger part of the overall equation of HP required to keep the mass in motion. At higher speeds, aerodynamics quickly become the most significant component of the equation.

    We're lucky because popups tend to have less frontal area (so a lower drag coefficient) than hard side trailers. To some degree that frontal area is in the turbulence wake or shadow of the tow vehicle, also improving the drag coefficient. But it still is there, and still matters a lot.

    So that explains some of the factors that weigh into towing at a constant speed on level ground. Additionally we're often pulling up a hill. Lifting weight up a hill means fighting the downward acceleration force of gravity; 9.6 M/s^2. That's a pretty big factor too, when climbing. And modern engines and cars are designed to be light weight so that they don't have to pull so hard up hills. But they're also often designed with high performance engines (my Explorer Sport's engine can produce up to 350HP). Under normal conditions pulling up a grade with no trailer, maybe I'm using 90HP. Add the weight of the trailer and pulling up that same grade maybe I'm using 180HP to maintain the same speed. Producing that burst of extra horsepower sucks down the fuel.

    And then there's the cost of accelerating from a stop. A 3200 pound tow vehicle needs to apply X amount of energy to accelerate from 0 to 60 in 30 seconds. It's going to need to consume X*2 energy to accelerate the 3200 pound tow vehicle plus the 3200 pound trailer from 0 to 60 in 30 seconds.

    Older vehicles, and heavy vehicles with really big gas guzzling engines see a smaller decline in fuel efficiency because they're already so heavy and inefficient. My Bronco weighs over 5000 pounds. So adding a 3200 pound trailer to it is only increasing its total mass by 60%, whereas adding a 3200 pound trailer to a 3200 pound tow vehicle increases its mass by 100%. Furthermore, a hill that I may consume 120 HP getting up at 70 MPH in my Bronco is simply not going to sustain 70 MPH while towing, because my max horsepower for that thing is 215. I would need 240HP (if climbing weight were the only factor) to sustain 70 MPH. Since I cannot pull 240 HP out of that engine, I can't consume double the fuel climbing that grade. I just have to slow down a bit. So I'm not getting twice as bad fuel economy on the hill. Another reason why my MPG on the Bronco only goes down about 2MPG vs over 4 for the Explorer Sport.

    And yet another factor is the aerodynamics of the tow vehicle. The explorer sport is designed to have a fairly low drag coefficient. And it has a smaller turbulence wake following it, so the trailer doesn't benefit from as much of a wind shadow.

    The Bronco, on the other hand, has the aerodynamics of a brick wall, is a larger vehicle so more of a turbulence wake, too. The trailer is more shadowed.
     
    Last edited: Oct 7, 2021
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  16. Eric Webber

    Eric Webber Well-Known Member Gold Supporting Member

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    I agree with this

    My V8 XC90 didn't notice a ~2000lb Coleman Santa Fe, but I lose about 20% on highway and "infinity" in residential stop and go with my ~4500lb Arcadia
     
  17. Dingit

    Dingit Well-Known Member

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    Eric makes a good point about the importance of the particular trailer. Some folks have nice low popups, some highwall popups, and some full height trailers (hybrid or not). Frontal area makes a huge difference.

    My fuel economy improves when I tow a popup because I drive slower. :)
     
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  18. Rusty2192

    Rusty2192 Well-Known Member

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    I think just locking out Overdrive while towing has more of an impact for me than the pup itself. We get about 24-25 normally with our van and anywhere from 16-19 towing the pup. The lower end of that is usually when I have the bikes and/or kayaks on the roof of the van. I got close to 20 on one trip this summer with a bare roof and speeds down around 65 mph and even 55 for a decent portion.
     
  19. Anthony Hitchings

    Anthony Hitchings Well-Known Member

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    in round nunbers it dropped from 20 mpg to 18 mpg in our 6-speed manual tranny 3.7 liter 2008 Jeep Liberty- these are from our current trip in the Southwest
     
  20. tfischer

    tfischer A bad day camping beats a good day at the office

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    With our Chrysler Pacifica I lose barely anything in some conditions, but wind will bring it down quickly. And wind + having our bikes on top the pup will significantly bring it down, several MPG.
     
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