EPA 2-Cycle Raw Data: 2017 Prius Prime

Discussion in 'Prime Fuel Economy & EV Range' started by Oniki, Jul 5, 2017.

  1. Oniki

    Oniki Active Member

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    I finally tracked down the raw EPA fuel economy for the Prius Prime.
    By way of background, the EPA has used a city test cycle and highway test cycle for decades. In recent years they added 3 other cycles meant to mimic more closely the speeds Americans travel, cold weather, and use of A/C. The fuel economy listed on the sticker in the window at the dealer is an amalgam of these tests in uneven proportions, and with additional fudging to again approach normative American driving habits.

    So why bother tracking down the 2-cycle data ?
    • For one, it gives a very good idea of possible fuel economy of the car if lower speeds (low 60s mph I think) are used on the highway and look ahead braking is used in the city during moderate weather.
    • Second, CAFE is based on the 2-cycle average.
    • Third, I was looking for another way to figure out the usable battery capacity of the Prime. As soon as someone tells me how the EPA range is calculated or I track it down on Google, the 2-cycle data will allow calculation.
    • Fourth, I wanted to see the city/highway break-down
    Data:

    Hybrid Mode

    1. City: 78.82 mpg
    2. Highway: 74.65 mpg
    EV Mode
    1. City: 16.26 kWh/100 miles
    2. Highway: 19.52 kWh/100 miles

    Impressive!
    The data discloses a remarkable highway fuel economy (thank you, low Cd) and continues to support the rule of thumb that advises EV use in urban driving and HV mode on the highway if the drive exceeds the battery capacity.
     
    #1 Oniki, Jul 5, 2017
    Last edited: Jul 5, 2017
  2. bisco

    bisco cookie crumbler

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    how can any test accurately portray what one particular driver will get for mpg's? after all, even the members posting here are all over the board with the same car.
     
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  3. Oniki

    Oniki Active Member

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    Drive like the test, become the test

    ;-)
     
  4. Prius from Dad

    Prius from Dad Senior Member

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    I totally agree.
     
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  5. bisco

    bisco cookie crumbler

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    best you can hope for is a realistic comparison between vehicles. but they all perform differently under different driving conditions.
     
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  6. drysider

    drysider Active Member

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    I do not see this as absolute mpg's. By using the same test for various models and manufacturers, you can make a reasonably sensible decision about who does what. I have consistently gotten much better mileage than the EPA rating on both my Gne2 and Gen3, as have many other drivers. At the same time, there are owners getting worse mileage. It depends on driving style, type of roads encountered, weather, etc. Use the EPA for comparisons and, if you are so inclined, use your own skills to maximize your individual mpg's.
     
  7. giora

    giora Senior Member

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    I am also interested in the raw data as being best for comparisons between various cars, so thanks for sharing.
    You do not need the raw data to calculate usable battery charge, you can calculate it from the sticker data:
    33.7/133*25=6.33 kWh from wall (i.e. before charging losses).

    Here are the EPA ultimate target bars to beat:):
    City: 6.33/0.1626=38.93 EV miles.
    Highway: 6.33/0.1952=32.43 EV miles.:ROFLMAO:
     
    #7 giora, Jul 6, 2017
    Last edited: Jul 6, 2017
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  8. bwilson4web

    bwilson4web i3 and Prime

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    Oh, you want bureaucratic mode, shift into "B".

    When I bought my first Prius, a used 2003 in Texas, I headed for the Louisiana border 50/50 like I stole it and keeping up with Texas drivers. In Shreveport I calculated 39 MPG and briefly thought about turning around and returning the broken car. But then I realized the EPA bureaucrats got 45 MPG so what is going on?

    The next leg, I got 54 MPG by driving 60 mph and on that trip home learned there is a 'knee in the curve': at 65 mph getting 52 MPG; at 70 mph, it only gave 49 MPG, and; 75 mph, 39 MPG. I never looked back but decided I could do at least as good as any EPA bureaucrat.

    Bob Wilson
     
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  9. bisco

    bisco cookie crumbler

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    otoh, i have never achieved more than 17 mpg in my dakota, no matter what techniques i employ, which is rated for 20 mpg.
     
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  10. Oniki

    Oniki Active Member

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    Thanks,

    Continuing in the same vein, the combined city/highway EV range is about 32 miles based on driving in 'EPA' 2-cycle mode before the fudge factors are introduced. It is not surprising that the EV ranges results posted in this thread from people interested in fuel economy are averaging towards that value.

    I agree with your 6.33 kWh calc from the wall, but that does not tell us usable battery capacity. One can certainly estimate pretty closely though as ~ 87% of that amount, or about 5.5 kWh. And as an aside, I'm looking forward to battery chemistry improvements and/or cooling that will allow Toyota to use more of the nominal capacity. An increase from 62.5% to 80% addressable (usable) capacity would increase our range 28%
     
    #10 Oniki, Jul 6, 2017
    Last edited: Jul 6, 2017
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  11. bisco

    bisco cookie crumbler

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    or keep the same range, and claw back the hatch floor.:)
     
  12. giora

    giora Senior Member

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    Actually 36 EV miles based on the raw data you have posted and 55% city, 45% highway driving.
     
  13. Estew808

    Estew808 New Member

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    I've been poking around on the Forum. I'm a Noob. I don't understand how I achieve 133 MPGe. Do I do that by driving in "EV Auto" mode?

    Would I then get 133 MPG on the first gallon of gasoline starting out with a full charge?

    Forgive me if this is a stupid question...
     
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  14. Estew808

    Estew808 New Member

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    I spoke too soon... I just found this:

     
  15. Tideland Prius

    Tideland Prius Moderator of the North
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    133mpg is the equivalent mpg of the electric portion of the car. It's basically a kWh/100 miles measurement converted into something familiar that Americans have used (mpg).

    The problem with the car's display is that it's a blended mpg readout so it will take into account gas and no gas miles into its calculation so it's apples to oranges comparison.
     
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  16. Estew808

    Estew808 New Member

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    Thanks!!

    Posted via the PriusChat mobile app.
     
  17. farmecologist

    farmecologist Senior Member

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    Wow I think I need a prime at some point after they enter the used market in a few years. (y)

    Our v (wagon) just isn't cutting it. I thought I could do significantly better than the EPA. However, lugging all that extra weight around ( vs the liftback ) really takes it's toll. In fact, I removed the rear seats in prep for an upcoming road trip. I didn't weigh the seats but they were pretty dang heavy! We have lightweight camping gear too so hopefully it will make a little bit of difference. We'll see!

    IMG_5580.jpg
     
    #17 farmecologist, Jul 24, 2018
    Last edited: Jul 24, 2018
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  18. Andyprius1

    Andyprius1 Senior Member

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    Double click the chrome icon! that’s good.

    It’s all Mpge, always. Even if you run out of charge, the car immediately starts charging and very shortly starts using again. The 199.9 is purely theoretical, it basically means infinite. The most realistic window is past averages, which in my case is always 150mpg, really: 150 MPGe. they omit the e, but, it’s always there.
    That 150 average for me is easy as my daily trip is mountainous, about 1300 feet. so I regain what has been used, free, or I charge if needed.
     
    #18 Andyprius1, Jul 29, 2018
    Last edited by a moderator: Jul 30, 2018
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  19. ziggy29

    ziggy29 Junior Member

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    The EPA's MPGe estimates are not infinite in EV mode, though. They are using an established formula to decide how many kWh are equivalent to a gallon of gas, basically. The calculation the Prime does for MPG on the dashboard does in fact compute "infinite" (199.9 or 999.9) when you are using *nothing* but EV mode.
     
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  20. Andyprius1

    Andyprius1 Senior Member

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    Remember these figures are all pretty much theoretical, all numerology. Even tho all my consumption bars are showing 150mpg, my average is 172 mpg. My total range was almost 1600 miles for the tank with one pip left. 1600 miles / 7 pips = 228.57 mpg. You see all these figures have a large variance between them.
    Now if I hand calculated at fill up, I’d get another figure. I’ll accept any figure, I’m happy. The cars phenomenal! And it will only get better.
     
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