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Towing milage 17MKE with 2018 GMC Sierra 1500 4wd SLT

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  • Towing milage 17MKE with 2018 GMC Sierra 1500 4wd SLT

    I am a new owner of a 17MKE 2020, i have notice that i am getting 6-7mpg, needless to say this is very disappointing. I have a 8 speed automatic transmission, with 5.3 gas engine, crew cab towing a 17MKE with empty tanks. I would appreciate input. I have tried lower gear such as 6 and 7 speed. I notice i get the best milage at gear setting 7 at 60mph. I normally get 20 mpg not towing.

  • #2
    Hi Jesseart! Welcome to the forum. I'm glad you could join us.

    Actually, I'm not all that surprised with your towing mileage. I tow a 34 foot Reflection travel trailer with a Ford diesel F350. Even with the diesel, I usually only get about 9.5 MPG. Gas powered tow vehicles usually get 20-30% less mpg when towing when compared to a diesel.

    What part of the country do you hail from, and are there a lot of hills? Do you frequently fight a lot of wind in your area? Hills and head winds really play havoc with my mileage.

    Jim
    The moderators for this site are not GDRV employees, but we do own GDRV products.

    Jim and Ginnie
    2017 Reflection 297RSTS

    Comment


    • #3
      Hi Jesseart,

      You mileage does seem low for towing a trailer weighing less than 6000 lbs at 60 MPH . . . unless you are at higher elevations, climbing hills or pushing into a head wind.

      I also tow with a (different) gasoline engine, but am pulling a much heavier trailer. On the 1500 mile more-or-less level (except for the Appalachians) trip back and forth to/from Florida/Canada, I typically average about 9.5 MPG. As you have mentioned, I tow in a lower transmission gear to keep my engine RPM at 2100 for 60 MPH. This seems to be the "sweet spot" for my turbocharged engine. I also run premium fuel when towing to help engine efficiency.

      Attached picture is from a recent trip between Ontario and Florida.

      Rob

      Attached Files
      Cate & Rob
      (with Border Collies Molly & Angel and their kitty Gracie)
      2015 Reflection 303RLS
      2014 Ecoboost F150 with Heavy Duty Payload Package
      Whitby, Ontario, Canada

      Comment


      • #4
        thanks Folks for your input. I am currently traveling in south Texas flatlands, yes some headwinds at times.

        Comment


        • #5
          Jesseart,

          I was not able to post earlier due to an init issue with my PC evidently.

          These numbers do not look right for what your towing. My 2015 GMC 6 speed with 3.42:1 final drive while towing a 2017 Imagine 2600RB will achieve 9-11mpg at 60-65mph. In the PA mountains, the fuel economy will settle in at 9mpg.

          Curious where are you towing? Also what is your non-towing numbers and at what speed?

          Also are you using the tow haul function? Your RPM while towing should be in the 1700 - 2200 range, depending on speed, for best efficiency.

          Jim
          Last edited by MidwestCamper; 01-31-2020, 08:43 PM.
          2017 Imagine 2600RB
          2015 GMC Sierra 4x4

          Comment


          • #6
            Originally posted by jesseart View Post
            I am a new owner of a 17MKE 2020, i have notice that i am getting 6-7mpg, needless to say this is very disappointing. I have a 8 speed automatic transmission, with 5.3 gas engine, crew cab towing a 17MKE with empty tanks. I would appreciate input. I have tried lower gear such as 6 and 7 speed. I notice i get the best milage at gear setting 7 at 60mph. I normally get 20 mpg not towing.
            Have you tried the mileage at higher speeds. I found that my Silverado has a sweet spot around 65 - 66 mph in tow/haul mode. At 60 - 62 mph I get 7 - 8 mpg and at 66 I get 9 - 10 on fairly flat grades. This was counter-intuitive but consistent. If I go faster the mileage starts going down. But, I do have the 6.0 L engine.
            Norm & Karla
            2019 Imagine 2150rb
            2018 Chevrolet Silverado 2500HD
            2016 - 2018 Hobie Kayaks

            Comment


            • #7
              Originally posted by Oregon Fun-Guy View Post

              Have you tried the mileage at higher speeds. I found that my Silverado has a sweet spot around 65 - 66 mph in tow/haul mode. At 60 - 62 mph I get 7 - 8 mpg and at 66 I get 9 - 10 on fairly flat grades. This was counter-intuitive but consistent. If I go faster the mileage starts going down. But, I do have the 6.0 L engine.
              Hi Norm & Karla,

              This makes some sense. My fuel economy is best at 2100 RPM, which is 60 MPH in 5th gear (of a 6 speed trans). Lower RPM drops me out of the turbo boosted range which needs more fuel and higher RPM needs more fuel. Every engine has a "sweet spot" where it runs best. Like your description, I get greater fuel consumption at 55 MPH and 65 MPH than I do at 60 MPH.

              Rob
              Cate & Rob
              (with Border Collies Molly & Angel and their kitty Gracie)
              2015 Reflection 303RLS
              2014 Ecoboost F150 with Heavy Duty Payload Package
              Whitby, Ontario, Canada

              Comment


              • #8
                The GM 5.3L has a torque curve that is almost identical to the older L96 6.0L where at around 2000 RPM the torque curve is rising and this area on the curve can provide the best efficiency. However there are trade offs where with a headwind, lower speed and RPM will win out.

                The 5.3L depending how you drive it will achieve between 19 and 24 mpg HWY with those out in Nebraska or Iowa achieving up to 30 mpg at steady state, 55 mph speeds in AFM as an example. These would be warm weather numbers as winter fuel (lean) and additional drag due to lower temperatures will drop MPG by 10-15% or so.

                For the OP, what is your final drive ratio?

                Jim
                Attached Files
                Last edited by MidwestCamper; 02-01-2020, 08:49 AM.
                2017 Imagine 2600RB
                2015 GMC Sierra 4x4

                Comment


                • #9
                  thanks again for all your inputs. i have tried deferent transmission gear setting and have concluded that at setting 7 (8 speed) at 55 mph, with highest octane gas i am getting close to 9 mpg traveling in south Texas flat roads with very little wind. so for future planning i need to estimate 7 mpg average. i will see if there are any upgrades i can do on my Gmc to improve the MPG such K&N air filter, exhaust, program the chip or get a new truck design for towing. We love out 17MKE RV, it tows great, the floor plan is ideal for my wife and I.

                  Comment


                  • #10
                    Originally posted by jesseart View Post
                    thanks again for all your inputs. i have tried deferent transmission gear setting and have concluded that at setting 7 (8 speed) at 55 mph, with highest octane gas i am getting close to 9 mpg traveling in south Texas flat roads with very little wind. so for future planning i need to estimate 7 mpg average. i will see if there are any upgrades i can do on my Gmc to improve the MPG such K&N air filter, exhaust, program the chip or get a new truck design for towing. We love out 17MKE RV, it tows great, the floor plan is ideal for my wife and I.
                    In regards to the K&N filter , I have tried this , twice , and had seen no improvement in performance or mileage. I tried this on 2 different GM gas engines. I have never tried a programmer or chip so I can not say that adding a programmer and a filter may help. Good luck.

                    Brian
                    Brian & Michelle
                    2018 Reflection 29RS Oct.17 build date, EMS-HW50C , Lippert Remote
                    2015 Chevy 3500HD CC LB Duramax , Reese Elite 18K

                    Comment


                    • #11
                      Originally posted by jesseart View Post
                      with highest octane gas i am getting close to 9 mpg traveling in south Texas flat roads with very little wind.
                      Hi jesseart,

                      9 mpg towing is not bad. I would stay far away from K&N filters or aftermarket calibration mods. The engineers who designed and calibrated your engine know far more about it's abilities, limitations and necessary safety margins than any aftermarket add-on supplier could ever hope to know. "Performance" chips typically use up built in safety margins to provide a little better performance at the risk of engine damage. Don't go there . . .

                      Rob

                      Cate & Rob
                      (with Border Collies Molly & Angel and their kitty Gracie)
                      2015 Reflection 303RLS
                      2014 Ecoboost F150 with Heavy Duty Payload Package
                      Whitby, Ontario, Canada

                      Comment


                      • #12
                        Originally posted by jesseart View Post
                        thanks again for all your inputs. i have tried deferent transmission gear setting and have concluded that at setting 7 (8 speed) at 55 mph, with highest octane gas i am getting close to 9 mpg traveling in south Texas flat roads with very little wind. so for future planning i need to estimate 7 mpg average. i will see if there are any upgrades i can do on my Gmc to improve the MPG such K&N air filter, exhaust, program the chip or get a new truck design for towing. We love out 17MKE RV, it tows great, the floor plan is ideal for my wife and I.
                        jesseart,

                        A few comments that may help.

                        1) In your manual GM will stress to use fuel from Top Tier suppliers. This does make a difference. Top Tier would be the major brands and can also be found online.

                        2) Moving up to high octane 93 octane fuel should not make a difference (actually will be less efficient on engines calibrated to 87 octane) where moving from 87 to 89 can help in some circumstances. Especially if not using top tier fuels.

                        3) A K&N air filter is a waste of money where the oils from the filter could contaminate the mass air flow sensor. Any claimed gains from them are small and at WOT which we do not spend so much time at.

                        4) A cat back system provides no benefit since the highest restrictor in the exhaust system is the catalytic converters. The only gain is noise and a loud system while running active AFM will not sound so good.

                        5) Tuners advance spark in order to burn premium fuel which will increase torque and power. The tune will however not increase torque and power on the intended 87 octane as the engine is already sparked for this fuel. GM can tell if a tuner has been used (even if removed) where the factory warranty will not be honored should an engine failure occur.

                        6) You may want to visit the dealer with a complaint on low FE. They will be able to check 02 sensors, knock sensors and other items such as brakes. Is this a TX truck and was it purchased new? If the truck has seen some time in the rust belt, an inspection for front brake rotor drag would not hurt. The GM caliper brackets can build up rust between the bracket and the stainless guide plates which can cause pad binding and increased friction.

                        Jim

                        9 mpg is within normal limits but your rig is smaller where I believe you should be seeing higher numbers. Most everyone here will see MPG at around 9-10 while towing larger rigs. What final drive ratio do you have?
                        Last edited by MidwestCamper; 02-04-2020, 08:45 PM.
                        2017 Imagine 2600RB
                        2015 GMC Sierra 4x4

                        Comment


                        • #13
                          Originally posted by Cate&Rob View Post
                          Don't go there . . .
                          And so dies another "hold my beer and watch this" moment...

                          Click image for larger version

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                          You're rarely that blunt, Rob. Any thought (not that I had any) of doing anything to my truck just went buh bye...



                          Forum moderators are not GD employees--we are volunteers and owners presumably just like yourself. Unless specifically mentioned otherwise, we have nothing to gain should you choose to purchase a product or engage a service we discuss on this forum.

                          Howard, 2017 Ford F-350 DRW, '19 315RLTSPlus

                          Comment


                          • #14
                            Originally posted by Cate&Rob View Post

                            Hi jesseart,

                            9 mpg towing is not bad. I would stay far away from K&N filters or aftermarket calibration mods. The engineers who designed and calibrated your engine know far more about it's abilities, limitations and necessary safety margins than any aftermarket add-on supplier could ever hope to know. "Performance" chips typically use up built in safety margins to provide a little better performance at the risk of engine damage. Don't go there . . .

                            Rob

                            In regards to the K&N filter , I have tried this , twice , and had seen no improvement in performance or mileage. I tried this on 2 different GM gas engines. I have never tried a programmer or chip so I can not say that adding a programmer and a filter may help. Good luck.

                            Brian
                            Well said Rob and Brian! The combination of these two posts should be put out for everyone to see. I have been looking at some of these aftermarket products for quite awhile, but I have always wondered why the big companies don't pick them up and use them in their products.

                            Norm
                            Norm & Karla
                            2019 Imagine 2150rb
                            2018 Chevrolet Silverado 2500HD
                            2016 - 2018 Hobie Kayaks

                            Comment


                            • #15
                              The "myth" that OEM powertrain engineers would purposely design and calibrate to less than maximum performance is fundamentally mistaken. Emissions are controlled in a very narrow range of part throttle operation. WOT (wide open throttle) performance is all about maximum power and your powertrain already has this, constrained only by what is necessary to protect the engine from destroying itself. The aftermarket will push into those limits of potential engine damage. Again . . . don't go there.

                              Rob
                              Cate & Rob
                              (with Border Collies Molly & Angel and their kitty Gracie)
                              2015 Reflection 303RLS
                              2014 Ecoboost F150 with Heavy Duty Payload Package
                              Whitby, Ontario, Canada

                              Comment

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