Steady State Speed vs Fuel Economy results

Discussion in 'General' started by seftonm, Mar 22, 2014.

  1. seftonm

    seftonm Veteran Staff Member

    I just organized them, Wayne did all the testing and data collection ;)
    xcel likes this.
  2. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

  3. joesgot4

    joesgot4 Well-Known Member

    Nice work on the graphs
  4. priusCpilot

    priusCpilot George

    Nice package deal!!

    I wish the ultimate car the Prius C had a graph. hehe
  5. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    Well... ;)
  6. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Okay, George just volunteered to do some testing on his Prius c !
  7. priusCpilot

    priusCpilot George


    How do I test and gather the data correctly?

    I have a SG2 but what steps will I need to take to be accurate in collecting data?
  8. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I think Wayne has described his procedure in the past. Maybe he can point you to the old post that has this. I kinda wanna do this with my car, too.
  9. PaleMelanesian

    PaleMelanesian Beat the System Staff Member

    What I did was this:

    Find a straight and level stretch of road. That's harder than it looks.
    For each speed point, get up to speed, set cruise control, then reset scangauge trip.
    At the ending point, make a mental note of the trip average mpg.
    Turn around and do the same the other direction.
    Write down the two numbers, then calculate the average of the two.

    Wayne's numbers don't always include a return trip because of varying situations, but as long as it's truly level and the wind is low it's a good reference point.
  10. seftonm

    seftonm Veteran Staff Member

    2013 Nissan Altima
  11. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I did a 55 mph CC test in 2009 with the Civic I still have today. I did a fill at a gas station very close to I-88 in Warrenville , then got on 88 going west and set the cruise. I did about 45 miles , then made a (illegal) U-turn and came back to the same gas station , same pump. The result was 49MPG , or about 2 MPG better than my 97 Civic. I don't remember if I was airing up my tires then. But I do know it was E10. Maybe I'll try again this spring
  12. seftonm

    seftonm Veteran Staff Member

    2014 Audi Q5 TDI

  13. fishnrib

    fishnrib Christian

    Wayne's Steady state 2013 HSH mph/mpg runs - each speed was 17 miles flat freeway with CC on and A/C off

    50 mph - 58.5 mpg
    55 mph - 55.7 mpg
    60 mph - 51.8 mpg
    65 mph - 46.7 mpg
    70 mph - 40.3 mpg

    My runs in a 2011 HSH after the ECU Update for 12 miles of rolling hills with CC on and A/C at 74 deg

    55 MPH - 55.9 MPG (45-55 MPH different hwy for 10 miles)
    57 MPH - 52.3 MPG
    60 MPH - 43.7 MPG
    65 MPH - 43.6 MPG

    As you can see if you can possibly go below 60 you can get almost 10 more MPG's.

    If you feel your HSH isn't up to par run your own test and compare it to ours. Make sure you start your test after at least a 15 minute ICE warn-up. Set your CC after up to speed then reset your instant MPG display and drive for at least 10 miles.
  14. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    Finally completed the 2014 Lexus ES300h Speed vs. Fuel Economy chart.


    The 2014 Lexus ES 300h is EPA rated at 40/39 mpg city/highway. Look where the ES 300h crossed its EPA highway rating.

    And like most Toyota/Lexus aFCDs, the ES 300hs is a bit optimistic. While the odometer was 3.7 percent short – itself a rather large positive offset and measured twice over significant distances – the aFCD vs. actual still indicated 2.3% optimistic. :(

  15. ALS

    ALS Super Moderator Staff Member

    I'll toss in my 97 Volvo 960 steady state cruise controlled results.

    Mostly to show just how much fuel mileage has jumped over the last 17 years.
    2.9L twenty four valve I6. Four speed auto box with OD

    I did some speed testing with my 1997 Volvo 960 when I was down in Naples in July of 07.
    Tires Michelin Energy + 4's set at 42 psi, 44 max sidewall.

    The test road is Rt 41 between Naples and Miami. I like this road for testing because it is very flat and most of the traffic now takes I-75 across the state. My starting point was the turn off for Everglades City. I ran 10 miles east then turned around and ran west back to my starting point.

    Scan gauge readings were as follows.
    Sg is extremely accurate to the pump fill numbers.
    As long as you stop at the next .25 after the first click of the nozzle.

    The MPG of each 20 mile run is as follows. Speed limit is 60 if I recall, so going ten over wasn't an option. ;)

    50 mph 35.4 mpg
    55 mph 33.9 mpg
    60 mph 31.15 mpg
    65 mph 28.5 mpg

    From experience running the speed limit of 70 mph with the AC on 25.5 mpg.

    Running 65 mph max from Pittsburgh to Naples (1170 miles) using E10 26.5 to 27 mpg is closer to reality. Same trip using E0 at a maximum of 65 mph I use to get between 29.25 and 29.75 mpg. E10's supposed 3% loss over E0, my ass try closer to 10% difference in fuel mileage.

    One thing I'm loving about this thread is no matter how you try to say it isn't so, speed does kill your gas mileage.
    Last edited: May 20, 2014
  16. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    I still get a kick out of newbies who come here and claim that it doesn't. :)
  17. xcel

    xcel PZEV, there's nothing like it :) Staff Member

    Hi All:

    Putting together the RX 450h review this evening and here is the Speed vs. FE graph. Given the 30/28 mpgUS city/highway rating for the AWD variant we are driving, I was not expecting much but it did break its EPA rating at a healthy 69.1 mph.


    Notice the minuscule offset? Maybe the engineers and marketing execs are done playing games as this is the second review drive in a row that had an accurate aFCD (< 1% error).

    A lot more to go on this.

  18. No Static At All

    No Static At All Active Member

    I don't get it either. These people just may be having trouble properly measuring things. . . . . . . .

  19. phoebeisis

    phoebeisis Well-Known Member

    So the PRIUS gets the BEST actual FE?
    And only a MT VW TDI very slightly beats is 59 vs 58 mpg at 60 mph
    and 48 vs 45 mpg at 70 mph
    In MPG?
    With the diesel fuel premium-
    can't see much point in a TD small car
    or a TD 1/2 ton truck-not with the Dodge delivering 30mpg at 60 mph and 25 mpg at 70 mph.

    The Dodge 1/2 ton is the most impressive graph.
    Never thought I would see a 30 mpg at 60 mph 1/2 ton pickup with 300 hp
    and from DODGE-not FORD who get in the mpg game much sooner

    Yeah the Dodge pickup wins the "hard to believe" prize.

    PS- Yes I know TD cars are more fun than the Prius-too bad Toyota insists on scrubbing the fun out of their cars. Bet it wouldn't be too hard for Toyota to "jack up" a Prius-higher performance 1.8(should be able to get 200+ hp from a 1.8 easily enough) and a jacked up traction motor-add 18" wheels-wider tires- better suspension-fancy "radio electronic computer crap" for youngsters-Voila' -
    give up maybe 10mpg or so?
    Unfortunately the Honda Accord-6 cylinder-probably gets close to 40 mpg at 60 mph-and it probably does 0-60 in well under 6 seconds-so maybe there isn't much point in a performance Prius-not giving up 10-15 mpg-
    Oh well talked myself out of it
    Last edited: May 30, 2014
  20. EdwinTheMagnificent

    EdwinTheMagnificent Legend In His Mind

    Charlie , there is something that can't be measured but is REAL and that is how easily the diesel cars can handle hills and mountains at speed. A Prius on level ground at lower speeds (65) might beat the diesel but will CERTAINLY struggle on hills.

    The diesel swallows up the mountains and leaves them in the distance.

    And at 60 MPH , the Prius will do 16-20 MPG better than an Accord V-6 ( my opinion).

    After saying all that , for my purposes and typical driving , the Prius rules.

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