Updated MPG vs MPH chart

Discussion in 'Gen 3 Prius Fuel Economy' started by bwilson4web, Jun 27, 2009.

  1. bwilson4web

    bwilson4web i3 and Prime

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    I've added three data points:
    [​IMG]
    The 19, 25 and 40 mph points were at 91-95F. I also revalidated the 70 mph data point and got a very similar number. Looks like I need:

    • 32-33 mph
    • 45 mph
    • 80 mph - repeat at summer temperatures w/o defroster
    • 55 mph - "I can't drive 55!"

    Bob Wilson
     
  2. SageBrush

    SageBrush Senior Member

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    Now Bob, I understand that it was a little bit humid and warm, but please tell me you didn't open a window. :cool: :D
     
  3. bwilson4web

    bwilson4web i3 and Prime

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    It was dry enough and I had a 19, 25 and 40 mph breeze. Yes, the windows were down at least enough to get a nice breeze. <grins>

    I grew up in Oklahoma in the days before car air conditioning and home cooling were fans and swamp coolers. In my Grandmother's case, a flour sack cloth stretched over the screen door occasionally doused with well water.

    [​IMG]

    [​IMG]

    It has been my experience that if the vehicle sustains any given performance for 10 miles, the Prius can sustain it until the tank is empty.

    The following is my first cell phone photo of the day showing the warm-up profile:

    [​IMG]

    This warm-up profile has me scratching my head:

    • EV mode - even during warm-up, the vehicle auto-stops the engine at lights. This is a very good thing!!!
    • nine minutes - I've seen 5 and now 9 minutes to achieve warm-up system efficiency. This remains a puzzle.
    Bob Wilson
     
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  4. F8L

    F8L Protecting Habitat & AG Lands

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    Thanks Bob!
     
  5. FireEngineer

    FireEngineer Active Member

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    Bob,

    I think you need to check your highway between 55 and 70MPH more, I've been seeing numbers at least 5 MPG better than yours.

    And I agree, the warm-up is not the greatest, almost the same as the Gen II. If you P&G real good you can keep the engine temp below 180F.

    Wayne
     
  6. bwilson4web

    bwilson4web i3 and Prime

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    Those were 'off the dealer lot' numbers and conservative:

    • tires not fully inflated
    • Shell 89, E10 - testing Shell 87, E10 now but straight gas tank was much better
    Instrumentation is needed but I've got so much on my plate now.

    Bob Wilson
     
  7. carz89

    carz89 I study nuclear science...

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    Bob - were you using any particular driving techniques (like P&G) to get maximum mileage, or were you just driving like your typical driver?
     
  8. bwilson4web

    bwilson4web i3 and Prime

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    I use cruise control to maintain the speed and try to find a relatively flat road, at least 10 miles. I then make two runs, one in each direction, and once I get to cruise speed, reset the trip meter.

    So none of my numbers try to include the acceleration load but this makes sense if you are doing a cross country trip. The steady-state, cruise control speed should ... within the temperature limits ... be reproducible.

    Bob Wilson
     
  9. VABeachPrius

    VABeachPrius Member

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    Bob,

    Will you overlay the data for the 2006 prius with the the 2010 prius. I am interested to see if there is a gain in MPG for steady state speeds of around 20-25 mph.

    I would have anticipated that the mpg for the 20 mph rage to be over 100. Were you limited to the gages in the car and not a scangage?

    Deadphish in va beach was kind enough to give me my first look at a 2010. It will be some time before I upgrade. I have really sped up my travels, but I am still holding a lifetime average of 64.3 mph for 405xx miles.

    I met the owner of Priority Toyota while talking to deadphish, I told him about my best tank and he wants a picture. He said he was going to forward it to toyota usa. We shall see.

    Initially, I was a beliver of P&G, but have found it is just easier to drive slow and anticipate traffic with pumped up tires and no AC.

    With the improvements in the gen 4 (technicality) i am sure my lifetime average would be in the 70's.
     
  10. bwilson4web

    bwilson4web i3 and Prime

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    Overlay is hard because it means mixing spreadsheets to do it right or fiddling with scales. Let me put them together and then flip between them until I can take time to do it right:
    [​IMG]
    [​IMG]
    The efficiency curve is for the 1.6L NHW11 and has all of the NHW20 low speed data points. I also have some high speed NHW20 data points in this chart:
    [​IMG]
    Take care with some of the data that was captured in high temperatures.

    I have something else in mind. <grins>

    I'm seeing a solid +5 MPG with the 2010 and that is with ordinary driving. I think a lot of us are still investigating this vehicle. <wink>

    Bob Wilson
     
  11. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    wow...better than 60 mph and still getting 60 miles per gallon!! TOTALLY FRICKING AWESOME!!
     
  12. Glider

    Glider New Member

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    The MPG vs PSI data I just completed can be used to help verify the Wilson MPG vs Speed data sets, and vice versa.

    The comparison looks reasonable. If you want to send me all your experimental conditions, Bob, maybe I can adjust something for fine tuning.

    Great data set!!

    - g
     

    Attached Files:

  13. bwilson4web

    bwilson4web i3 and Prime

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    No problem sharing my data but the initial mileage points were manually recorded. I'm moving towards GPS recorded driving profiles for the PnG tests.

    The first tests were run on the trip home from the dealer and the conditions were pretty much as described in the graph legend. I ran two passes, same route but opposite directions to normalize the altitude and wind effects. I just wanted a baseline. But one of the outliers, the 80 mph point, may be not just a question of cooler temperatures and use of defrost.

    This may be the first indication of a 'knee in the curve' for aerodynamic drag:
    [​IMG]
    A speed of 34 m/sec ~= 78 mph. Notice I seemed to run into a mileage hit at 80 mph:
    [​IMG]

    Bob Wilson
     
  14. Glider

    Glider New Member

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    I guess I didn't explain myself very well. I was trying to compare my two speed points with your complete data set, not the other way around. I thought that if I knew all your experimental parameters, like tire pressure, etc., I could adjust *my* points and see if they matched up with your data even better. Sorry about that.

    Yes. This is interesting. Reminds me of the way bubbles and air-stream reattachment points move around with airspeed on airfoils. AS a matter of fact, I often muse over the appearance of the upper surface of the Prius. Looks a lot like the top of an airplane wing - for obvious reasons!

    Good luck with your work!

    - g
     
  15. bwilson4web

    bwilson4web i3 and Prime

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    I'm thinking P-51, laminar flow wing that moved the maximum thickness back to the middle of the cord. <grins>

    Bob Wilson

    ps. Enjoy the spreadsheet.
     

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  16. dhs

    dhs New Member

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    What I find interesting about the graph is I have a 30 mph data point, except, I have too many variables outside of my control to call it a data point (other traffic, lights, etc). But, when I hit everything correctly, I am able to do between 90 and 92 mpg at 30. That has happened twice since I got my prius, and usually when I go to work before rush hour. (Today, I got up a 6:30, left the house at 7:00, and was in rush hour. I averaged 83 once the car warmed up...72 including the warm up time).
     
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  17. DaveinOlyWA

    DaveinOlyWA 3rd Time was Solariffic!!

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    i dont have any real way of recording "accurate" info, but i do have an advantageous work schedule (i have tues, thurs and Saturday off) which allows all daycare to be split between, me, mother and grandmother.

    this also allows me to get the "business" chores done much more efficiently. i shop during off hours, rarely have to wait in line more than a few minutes, etc.

    so, despite the fact i live in the state capital, with its associated traffic jams during rush hour. (granted not a big town by most standards) its an urban area which basically has 3 small towns separated by a few miles of country/suburban roads, i have the opportunity to drive at relatively low steady speeds.

    now, P&G is not that easy to do because there is some traffic and the best routes are single lanes, but can do 35 or 40 mph for good stretches like 4-7 miles with little interuptions.

    but anyway, the SOC plays such a huge part in what my mileage will be. unlike the SPM which would go from EV to gas mode every minute or so in CC, the 2010 will usually run the SOC to 2 bars before recharging if left in CC.

    so to combat the radical swings in SOC, i frequently try to force the ICE on the vary the speed to run a slight charge to the battery and still try to maintain an instantaeuous mpg of 50+.

    iow, the usual "just drive conservatively and let the car do the thinking" does not work very well at speeds under 40 mph. the redesign making it more efficient at highway speeds seems to have sacrificed a little of the process at lower speeds.

    now, not the end of the world, using the HSI, its easy to nudge it past the center point to kick the ICE back on, and what i have been doing lately is trying to make sure i shut down with at least 5 bars. unlike the SPM, manipulating the SOC is rather easy. i noticed if parking with SOC at 2-3 bars, the mileage penalty was hard to overcome the next time i drove it.
     
  18. hektorr

    hektorr New Member

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    Interested in US - litres and UK - litres conversion?
    See attachment
     

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  19. unkprius

    unkprius Member

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    I think I could more easily move to/figure out in my brain the metric side in this situation if I first switched to KPL, kilometers per liter(litre) which makes more equivalent sense to MPG. But this measurement doesn't seem to be used. Bummer.
     
  20. Mendel Leisk

    Mendel Leisk Senior Member

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    Just a tip, to convert either value, mpg to liters per 100 km, or the reverse:

    235.214583 divided by value

    For convenience you could round that number a bit more, say to 235.2
     
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