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60-50mph Pulse&Glide with Draft vs. 60-40mph Pulse&Glide without draft

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  • 60-50mph Pulse&Glide with Draft vs. 60-40mph Pulse&Glide without draft

    So I decided to take advantage of a trip, and thought it would be a good chance to answer some questions I had in regards to the efficiency of drafting with P&G vs P&G with longer coast downs.The experiment was conducted as follows.

    I filled up at the gas station that's about .2 miles from the on ramp just outside of Lowell, MI at 3:30 p.m. The temperature was 83F and tire pressure 60psi on the rears, 55 on fronts. I proceeded to enter the on ramp following a semi tractor that I was hoping would serve as a viable candidate for my test. Sure enough he was very consistent at a 55mph speed and I was able to do 60-50mph P&G for about 90% of my trip there. I was careful to maintain at least 3 car lengths, as I felt any less would be unsafe. Average speed up and coast down was 15 seconds for each. I filled up just off the freeway for .846gal for a mpg total of 72.9mpg for portion A of the test.
    I proceeded to do my errands in Lansing which was less than a mile from the fill station and just topped off again before heading home.
    I started toward home on the B portion of my test at 6:45 p.m. with a temperate of 84F. I proceeded to speed up to 60mph and coasted down to 40mph each time average speed up and coast was 30 seconds for each. I was able to hit my target 90%+ of the time and came close to hitting it on the times when I missed. A couple times I started my speed up early at 45mph because of traffic requirements, and likewise also allowed myself to coast to 35mph an equal number of times as traffic allowed to make up for the times when I had to start it earlier. All highway portion of this testing was done in 5th gear.
    The B portion of the test required .728gal on 61.7 miles for a total of 84.75mpg. While I understand that this size sample is subject to potential fill errors, I did my best to fillup the exact same way and feel confident that I was able to glean some valuable insight into how to best maximize driving efficiency with my 93 Ford Festiva 5Speed. Hopefully this can be of some use to you

    Results:
    A portion (60-50 P&G with drafting semi): 61.7 Miles on .864Gallons = 72.9mpg
    B portion (60-40 P&G no drafting): 61.7 Miles on .728Gallons = 84.75mpg
    (For full details read above)

    Feel free to ask any questions that I didn't answer in the description.
    Last edited by mikeyjd; 05-30-2013, 08:47 PM.
    My Fuel Log



    See post #10 for my tips on fuel economy

  • #2
    I'm pretty sure you have to get much closer than 3 car lengths to take advantage of drafting. I wouldn't suggest drafting semi's on the hwy. They don't like it and even 3 car lengths is not a safe distance.
    -Rafe-

    Things I have for sale.
    Random Festiva Parts
    Festiva Non-Swoopy Power Drivers Mirror

    Comment


    • #3
      I don't see pulse and glide being a good idea on the interstate.
      91 Festiva L "Erika" b3t swap on the way
      06 Jeep Cherokee Overland
      95 Aspire (sold)

      Comment


      • #4
        Originally posted by Prafeston View Post
        I'm pretty sure you have to get much closer than 3 car lengths to take advantage of drafting. I wouldn't suggest drafting semi's on the hwy. They don't like it and even 3 car lengths is not a safe distance.
        Aerodynamic drag can be reduced by as much as 20% from 80ft at 55mph. 3 car lengths at maximum awareness, for short spurts, isn't altogether unsafe in my opinion. I would say if you were doing constant throttle at 3 car lengths it would be totally different, but I was at 3 car lengths for 3-4 seconds with my foot over the break pedal before coasting back to a further distance of up to 120ish ft (at which length all noticeable aero gain is diminished).

        Originally posted by Chobobulous View Post
        I don't see pulse and glide being a good idea on the interstate.
        It can be done in a safe and considerate manner, especially on less busy highways. I took traffic situations into careful consideration during these tests.
        My Fuel Log



        See post #10 for my tips on fuel economy

        Comment


        • #5
          Fill errors or no, you are proving what P&G can do for someone! Very nice work Mikey.

          What might also be good is to draft motor homes, without P&G. Just keeping a steady distance like 60 feet or so.
          90 Festy (Larry)--B6M (Matt D. modified B6 head), header, 5-speed, Capri XR2 front brakes, many other little mods
          09 Kia Rondo--a Festy on steroids!

          You can avoid reality, but you can't avoid the consequences of avoiding reality--Ayn Rand

          Disaster preparedness

          Tragedy and Hope.....Infowars.com.....The Drudge Report.....Founding Fathers.info

          Think for yourself.....question all authority.....re-evaluate everything you think you know. Red-pill yourself!

          Comment


          • #6
            Originally posted by TominMO View Post
            Fill errors or no, you are proving what P&G can do for someone! Very nice work Mikey.

            What might also be good is to draft motor homes, without P&G. Just keeping a steady distance like 60 feet or so.
            I have done this before with results in the low-mid 60's on single trips at 60-80ft following distance, steady state 60ish mph. It's definitely good, but not nearly as good as pulse and glide for the sake of max efficiency. As a general rule I do a mixture of both in every day driving depending on what the situation allows for
            Last edited by mikeyjd; 05-30-2013, 10:15 PM.
            My Fuel Log



            See post #10 for my tips on fuel economy

            Comment


            • #7
              i'll be on a trucks butt for hours at 65 and never see better than 42mpg..... i wonder what's different.
              Trees aren't kind to me...

              currently: 2 88Ls (Scrappy and Jersey), 88LX, 90L(Pepe), 91L, 91GL (Skippy) 93 GL Sport (the Mighty Favakk), 94 (Bruce) & 95 Aspire SEs, 97 Aspire (The Joker),
              94 Justy 4WD, 87 Fiero GT, plus 2 parts cars. That's my fleet.

              Comment


              • #8
                Congrats on getting over the 60mpg average fill up, btw!

                And FestYboy, he's got a couple threads where he's explained what he's done to his car...it's more than P&G that's getting him over 60mpg!
                -Rafe-

                Things I have for sale.
                Random Festiva Parts
                Festiva Non-Swoopy Power Drivers Mirror

                Comment


                • #9


                  Post #10 tells you about his car.
                  90 Festy (Larry)--B6M (Matt D. modified B6 head), header, 5-speed, Capri XR2 front brakes, many other little mods
                  09 Kia Rondo--a Festy on steroids!

                  You can avoid reality, but you can't avoid the consequences of avoiding reality--Ayn Rand

                  Disaster preparedness

                  Tragedy and Hope.....Infowars.com.....The Drudge Report.....Founding Fathers.info

                  Think for yourself.....question all authority.....re-evaluate everything you think you know. Red-pill yourself!

                  Comment


                  • #10
                    Originally posted by FestYboy View Post
                    i'll be on a trucks butt for hours at 65 and never see better than 42mpg..... i wonder what's different.
                    Gas mileage plummets after 60mph (starts going down after 50mph) with these short final drive reduction gears. A cam shaft retardation would improve that somewhat.
                    My Fuel Log



                    See post #10 for my tips on fuel economy

                    Comment


                    • #11
                      Originally posted by FestYboy View Post
                      i'll be on a trucks butt for hours at 65 and never see better than 42mpg..... i wonder what's different.
                      Terrain. And you're going 65.

                      My best was 53 mpg following a semi across Michigan at around 60 mph.
                      91GL BP/F3A with boost
                      13.79 @ 100, 2.2 60' on 8 psi and 155R12's

                      Comment


                      • #12
                        Originally posted by FestYboy View Post
                        i'll be on a trucks butt for hours at 65 and never see better than 42mpg..... i wonder what's different.
                        Hmmmmmm....perhaps you should take your car to a good mechanic to have it checked out....
                        90 Festy (Larry)--B6M (Matt D. modified B6 head), header, 5-speed, Capri XR2 front brakes, many other little mods
                        09 Kia Rondo--a Festy on steroids!

                        You can avoid reality, but you can't avoid the consequences of avoiding reality--Ayn Rand

                        Disaster preparedness

                        Tragedy and Hope.....Infowars.com.....The Drudge Report.....Founding Fathers.info

                        Think for yourself.....question all authority.....re-evaluate everything you think you know. Red-pill yourself!

                        Comment


                        • #13
                          Originally posted by bhazard View Post
                          My best was 53 mpg following a semi across Michigan at around 60 mph.
                          That's pretty good, for a non-aero-modified Festy.
                          90 Festy (Larry)--B6M (Matt D. modified B6 head), header, 5-speed, Capri XR2 front brakes, many other little mods
                          09 Kia Rondo--a Festy on steroids!

                          You can avoid reality, but you can't avoid the consequences of avoiding reality--Ayn Rand

                          Disaster preparedness

                          Tragedy and Hope.....Infowars.com.....The Drudge Report.....Founding Fathers.info

                          Think for yourself.....question all authority.....re-evaluate everything you think you know. Red-pill yourself!

                          Comment


                          • #14
                            i should have specified that i was in Scrappy at the time (B6 swap with cam)... i did get 44 in the 93 sport comming home from Ohio at 70+ and 42ish in Bruce with the a/c on (same trip and speed)....
                            Trees aren't kind to me...

                            currently: 2 88Ls (Scrappy and Jersey), 88LX, 90L(Pepe), 91L, 91GL (Skippy) 93 GL Sport (the Mighty Favakk), 94 (Bruce) & 95 Aspire SEs, 97 Aspire (The Joker),
                            94 Justy 4WD, 87 Fiero GT, plus 2 parts cars. That's my fleet.

                            Comment


                            • #15
                              Brad is right, terrain is a huge deal on MPG. I dare anyone to come down here and consistently get anything over 45 driving in and around my town. But still, a 60average is AWESOME! No matter where you are
                              No festiva for me ATM...

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