Ad Hoc 0-60 mph

Discussion in 'Gen 4 Prius Technical Discussion' started by bwilson4web, Nov 21, 2015.

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  1. GasperG

    GasperG Senior Member

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    Bob, I think you missed the PRIUS ECO version, it's in the data behind Prius C ;)

    Then we have:
    A (lbf) Cold - 19.034
    A (lbf) - 17.13
     
    #61 GasperG, Jan 21, 2016
    Last edited: Jan 21, 2016
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  2. JamesBurke

    JamesBurke Senior Member

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    Answering my own? Yes target values Ref. http://avt.inel.gov/pdf/prog_info/SAEWorldCongress2013MassImpactPaper.pdf

    Values for Target Coef B (lbf/mph) for the 10-ZW1H given in the EPA doc. are inconsistent with values given in that column across many other vehicles. Decimal in the wrong place or just wrong? And how do they get negative values for this?

    Looking across all yr 14, 15, and 16 values for Coef B are all over the place even for the same model. The effect of vehicle weight per tire size and type on rolling resistance?

    The new Prius still looks good against the others.
     
    #62 JamesBurke, Jan 21, 2016
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  3. bwilson4web

    bwilson4web BMW i3 and Model 3

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    My understanding is the 'target' coefficients come from the roll-down. The second set are calculated with the weight to set the dyno parameters.

    Bob Wilson
     
    #63 bwilson4web, Jan 21, 2016
  4. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Thank you!

    I've updated the charts and replaced the first version. You'll need to reload the page to clear local browser cache.

    Bob Wilson
     
    #64 bwilson4web, Jan 21, 2016
  5. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Brother! Not all SAE papers are worth it but anyone who cites one gets a +1 in my book.
    This is an area that still has me curious. My current hypothesis is generating the coefficients comes from an instrumented roll-down test. The raw values are plugged into a function/formula and 'curve fitted' to generate the coefficients. If you go from roll-down to coefficients, good news. But some of us have noticed that curve fitting parameters can be 'tweaked' to fit the data.

    There will always be a certain amount of variability in any test. If I were doing it, I would want five runs each way, toss the highest and lowest, and average the remaining three. Then I would do the curve fitting. But I've not found a good description of how the curve fitting is done.

    Bob Wilson
     
    #65 bwilson4web, Jan 21, 2016
  6. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Edmunds had a nice write-up on 0-60 times: 2010 Toyota Prius Road Test

    Not All Numbers Are Better
    With a bigger gasoline engine and a more efficient transaxle, Toyota predicts a 9.8-second 0-60-mph time for the 2010 Prius. That's about a half-second quicker than most of the second-generation cars we've tested.

    However, our best 0-60 run in our base-model tester is 10.1 seconds. If you allow 1 foot of rollout as on an NHRA drag strip, the time drops to 9.7 seconds, which supports the company's claim. Fact is, though, several of the second-gen Priuses have come very close to our 2010 Toyota Prius test car's 17.3-second quarter-mile time and 79.7-mph trap speed.    ​

    Bob Wilson
     
    #66 bwilson4web, Jan 21, 2016
  7. Felt

    Felt Senior Member

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    I've mentioned elsewhere, I well remember in 1955 when Chevrolet introduce their first modern V-8, the magazines were all excited about a 0 to 60 mph of 10 seconds. I well remember how important that was to me then. Not so much now, 60 years later.
     
    #67 Felt, Jan 21, 2016
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  8. bhtooefr

    bhtooefr Senior Member

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    Here's another video, showing a 0-189 km/h run (title says 0-180 km/h, but based on the sound, the driver keeps their foot in it to 189):

     
    #68 bhtooefr, May 7, 2016
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  9. GasperG

    GasperG Senior Member

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    If it's EU spec Prius then 189 km/h is 180 km/h actual. The car ECU has the right speed, but on MFD it's off on purpose, it's like this on all EU spec cars, it has something to do with regulation, don't know exactly.

    Also note that error is not necessarily 5% at all speeds, on Gen 3 with 15" the error at 100 km/h is around 8%.
     
    #69 GasperG, May 8, 2016
  10. pakitt

    pakitt Senior Member

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    With 17" wheels I get typically well above 5% error at the speedometer and more around 10% at higher speed vs what the GPS reports.
    This means that when flooring the car on a flat Autobahn stretch, I get to 188-189km/h, and when downhill I have even managed to see a 190km/h.
     
    #70 pakitt, May 18, 2016
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