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A different way to calculate MPG for the Plug-in

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by CraigCSJ, Jan 31, 2012.

  1. CraigCSJ

    CraigCSJ Active Member

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    For 100,000 miles my 2004 Prius averaged 48 MPG. A year ago I added a 4 KWh Enginer plug-in kit.

    My last tank was 514 miles using 7.105 gallons of gas at $3.80 per gallon (Southern California). This calculates to 72.34 MPG, but doesn't take into account that I also purchased 61 KWh of electricity, determined by my Kill O Watt meter placed at the electrical plug. Dividing last month's electric bill by the KWh purchased tells me that I pay the utility Edison $0.15 per KWh (all my use is at the lowest tier so I don't have to add a higher tier's cost). That means the 61 KWh for the Prius cost $9.15. Dividing that cost by the $3.80 cost of gas means that for that money I could have bought 2.41 gallons of gas for the Prius. If I had done that instead of buying electricity, I would have gone 514 miles using 9.513 gallons of gas, which works out to only 54.03 MPG. Since my Prius gets 48 MPG for me without electricity, the 54.03 MPG represents a 12.6% improvement over gas alone.

    This method tells me how far my car will take me for the cost of one gallon of gasoline.

    I wonder how the new Plug-in Prius will compare.
     
  2. jbrad4

    jbrad4 Active Member

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    My Plug-In will run a little cheaper here in North Texas where I have a contract for a flat 9.5 cents/kWh.
     
  3. gwmort

    gwmort Active Member

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    Just out of curiosity, how long would it take to offset the price of the kit saving 12.6% on your fuel cost every month?
     
  4. bisco

    bisco cookie crumbler

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    that is the calculation i am comfortable with as well. that is disappointing, i was hoping electric mileage would be 100% more efficient than gas. roughly estimating, i have been thinking if i can go 14 miles (my commute) on pure electric, and it takes 3kwh to recharge, at .10/kwh here, that's about 5 miles for .10 or 50 miles for a dollar. with gas in mid to high three's, i'm at about 3 dollars for 50 miles. i guess i'll have to wait and see although you're paying 50% more for electricity that me currently. (no pun intended:p)
     
  5. DianneWhitmire

    DianneWhitmire High PRIUStess

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    ...do what I plan to do: plug it in everywhere, work, etc.
     
  6. John in LB

    John in LB Life is good

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    I plan on sneaking over to Dianne's house and plugging it in over there... (while she is at work, plugging hers in over there...) Doing that way, what mileage does Dianne get???

    We have already established that it's not the economics that work out for this thing.... its the STICKER....
     
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  7. DianneWhitmire

    DianneWhitmire High PRIUStess

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    LOL John!
    That reminds me of the day about 10 years ago I got home from work very early afternoon - obviously unexpectedly - and saw my next door neighbor's hose hooked up to my water spout outside and extending over to HIS front lawn...watering to his heart's content.
    That's funny!
    :D


     
  8. ETC(SS)

    ETC(SS) The OTHER One Percenter.....

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    I expect to hear more "theft of electricity" stories in the future.

    I had a coworker some years ago who bought an electric scooter (he lived REAL close to the office!) and he used to plug it into an exterior plug. One of the technicians in the office got up all over him for 'stealing electricity from the company' UNTILL.....

    I took her to her desk and somewhat impolitely showed her:
    1. 1,500 watt heater, plugged in and running. (she was cold natured)
    2. Dorm Refrigerator..ditto
    3. Radio...plugged in and playing 24/7
    4. Coffee Maker.
    aaaaand a personal halogen desk lamp. Always plugged in and on. (she couldn't read her novels by the ambient office lighting.... :rolleyes:)


    My co-worker never got bothered about his scooter again. ;)
     
  9. iRun26.2

    iRun26.2 New Member

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    Maybe I will drive my car home to Minnesota. The first stop, of course, then will be at Dianne's place to charge. :)

    (Perchè no?)
     
  10. bisco

    bisco cookie crumbler

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    everywhere free.;)
     
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  11. drinnovation

    drinnovation EREV for EVER!

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    Given what you do you might call it MPG$.. showing its MPG on a $ converted basis.

    I personally prefer to convert away from MPG into MPD (mile per fuel dollar), then non-gas vehicles, PHEV, gas, diesel, even public transit can be compared.
     
  12. Allannde

    Allannde Just a Senior

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    Now that idea really makes sense to me! It is like, why haven't we been doing this all along?

    I often find that your posts do not harmonize with my thinking, but I read them anyway because they are thoughtful and it is possible to learn, especially if your view does not validate mine.

    You really nailed it with this one.
     
  13. daniel

    daniel Cat Lovers Against the Bomb

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    Theft of electricity is common in Mexico. People connect directly to the overhead lines somehow. Often at outdoor markets.

    I pay six cents per kWh, and get around 3 miles per kWh, so around two cents per mile. That's 50 miles per fuel dollar.

    At $4 per gallon (I actually don't know what it is here) that dollar would get me 1/4 gallon. 50 miles for 1/4 gallon is 200 miles per gallon equivalent.

    If gas is $3.50 the dollar would get me 2/7 of a gallon or 175 mpge.

    In winter, with my short drives, I use a lot of heat (once the cabin is hot I turn the heat way down, but on short drives the heating factor is higher.) I'm not sure exactly how much is used, but my wintertime mpge is probably down around 150 mpge, using the cost-based method of the OP rather than an energy-based method.

    The fuel savings will never pay for the cost of the car over a Prius, but the smugness of driving pure electric is priceless. And the rocket-class acceleration is a thrill.
     
  14. usdmattiphone

    usdmattiphone Member

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    I noticed that in the parking garage at my apartment complex there is a wall plug only a spot away, i'm wondering if the complex will let me use that outlet. I am worried that they'll think it's on par with a normal plugin vehicle though with a lot higher demand and tell me no. I'm really hoping they get started soon installing the 50 charge stations at my work they were telling me about, otherwise i'll be buying a PiP and essentially using it as a normal prius as I won't be able to plug it in much of the time.
     
  15. daniel

    daniel Cat Lovers Against the Bomb

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    Show them the specs, how many kWh the PiP can hold, and offer to pay for the electricity on the assumption that you'll be completely filling the battery every night (worst-case scenario). It should be just pennies.

    A bigger problem will be the possibility that someone steals your cord. EVs are going to need a locking mechanism for the cord.

    My EVs have had no such mechanism, but I only plug in in my garage, so it's not an issue for me. But as more people need and use public charge spots, it will become an issue.
     
  16. iRun26.2

    iRun26.2 New Member

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    Unfortunately one stolen cord can not be made up (financially) by even many free charges.

    I sure wish that the car connection would be locked. In future EVs (five years from now), I certainly expect that will be the trend.
     
  17. Tracksyde

    Tracksyde Member

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    I posted this somewhere here before, but I couldnt even find it myself.. but I think this should be available here (and if not, it should be made available).. but this would nice to have:
     

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  18. usdmattiphone

    usdmattiphone Member

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    Isn't it theoretically possible for my to run an extension cord (rated at over 16A of course) from the wall, and into my hatchback (which i assume should have enough clearance around the edge seals to still close but accomodate a cable) so that only the J1772 connector and the extension cord are coming out of the back of the vehicle while the body of the charger is inside the car?
     
  19. andi1111

    andi1111 Member

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    This is my charging box I had installed in our garage.

    I have a keylock, with which I can lock the box, but leave the charging cable plugged and going through the cut in the box.

    I charge my Vectrix this way
     

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  20. iRun26.2

    iRun26.2 New Member

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    I'm not worried about someone stealing the cord from my garage, at home (I plan to charge with my garage door closed...I assume that is OK). I'm concerned with someone unplugging it and taking it at a public charging station (when I am not there). I may gamble sometimes, and leave it unprotected. I bet a lot of people won't even know what it is until more EVs and PHVs are on the road.

    Maybe some potential thieves would be worried that an alarm will go off if disconnected. :)