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MPG/MPGe per Passenger

Discussion in 'Gen 1 Prius Plug-in 2012-2015' started by iplug, Aug 17, 2013.

  1. iplug

    iplug Senior Member

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    For those of us MPG/MPGe junkies, I thought of a new metric that would be nice to have in the PiP - MPG/MPGe per passenger.

    Consider retired4999’s stats, currently at 163.5 MPGe. With this amazing efficiency, there is the theoretical potential to get over 600 MPGe per passenger if one used the PiP for regularly commuting with 4 occupants. Of course MPGe will go down a bit with the extra weight.

    Perhaps the vehicle could detect additional passengers simply by noting which seatbelts are used. The sensors/electronics are already there, so this shouldn’t take much of an engineering effort.
     
    #1 iplug, Aug 17, 2013
  2. jnet

    jnet Member

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    I think you meant over "600 passenger-MPGe", not "600 MPGe per passenger". You are taking 166 x 4

    A van carrying 5 passengers would get about 100 passenger-miles per gallon.
     
    #2 jnet, Aug 17, 2013
  3. iplug

    iplug Senior Member

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    Someone else can weigh in here, but it seems this should still be MPGe per passenger. Yeah, even low MPG vehicles that carry lots of passengers should get high MPG per passenger.

    So lets say someone got 100 MPGe driving solo. If we ignore losses for weight, and one drove all of these miles with a total of 4 occupants, one would get 400 MPGe per passenger.

    If I had to guess, many PiP owners use the vehicle routinely as a commuting car for near daily short trips. For those of us with families who also take some long road trips a few times a year, this would significantly increase the MPG per passenger.
     
    #3 iplug, Aug 17, 2013
  4. jnet

    jnet Member

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    Here's the math 4 passenger x 166 mpg = 664 passenger-mpg. So, it's not 664 mpg/passenger because we are not dividing. We are just multiplying.

    Likewise, if a job takes 10 hours to finish using 4 men, that's 4 men x 10 hours = 40 man-hours. It's not 40 hours/man.

    A van full of people will be more efficient than a Prius with just the driver. The van will have about 140 passenger-mpg (7 x 20) while the Prius will have about 50 passenger-mpg.
     
    #4 jnet, Aug 17, 2013
  5. iplug

    iplug Senior Member

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    We are dividing, but I think I see the breakdown in communication. I should have been less vague, but this seems to be the source of confusion:


    x = miles
    y = gallon
    z = passenger


    Herein I mean to imply miles per (gallon per passenger), NOT miles per gallon (per passenger), so:
    x/(y/z) = (zx)/y

    In this case:
    Miles per gallon per passenger = Passenger Miles per gallon

    Technically [(miles per gallon) per passenger] and [miles per (gallon per passenger)] are different things.

    So, if said vehicle gets 166 mpg and there are 4 occupants (passengers), by this definition it gets both 664 passenger miles per gallon and 664 miles per gallon per passenger.

    You referenced the unambiguous and standardized term, passenger miles per gallon (PMPG), so I should have used that term to avoid confusion.
     
    #5 iplug, Aug 18, 2013
  6. wjtracy

    wjtracy Senior Member

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    ...I'd rather talk about miles per gallon and miles per kWhr. IN any case sounds like Retired4999 is not using too much of either, somehow.
     
    #6 wjtracy, Aug 18, 2013
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  7. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    I agree that calculations like this are important. It shows how a massive track hauling freight can be much more efficient that a Prius. And Warren Buffett illustrated this same sort of concept when he said the railroads are actually a very green industry.
     
    #7 markabele, Aug 19, 2013
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  8. jnet

    jnet Member

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    I'm not an experts in trains. But I think here are the two main reasons why transportation in rail is very efficient. 1) Ultimate LRR wheels. Train cars use steel wheels, not rubber tires like cars and trucks. 2) Ultimate drafting. Besides the front engine, all following train cars do not have to fight wind resistance.
     
    #8 jnet, Aug 19, 2013
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  9. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    That, and they rarely have to start and stop.
     
    #9 markabele, Aug 19, 2013
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  10. John H

    John H Senior Member

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    I think the metric would be Passenger Miles per Gallon Equivalent, or PMPGe.
     
    #10 John H, Aug 19, 2013
  11. jnet

    jnet Member

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    In one of the commercials, a rail company claims that a train could move 1 ton of cargo 500 miles per gallon of fuel. The efficiency would be 500 ton-mpg or equivalent to 2500 passenger-mpg. There is a huge number that no other form of transportation could beat.
     
    #11 jnet, Aug 19, 2013
  12. John H

    John H Senior Member

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    The problem with the tons-miles/gallon metrics is that they don't capture the time value of the goods being transported.

    We fly ourselves and goods because of such considerations. If we don't assign a time value then we would walk or ride a bicycle instead of climb into a vehicle.
     
    #12 John H, Aug 19, 2013
  13. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    For many products time consideration isn't that important, especially when there is literally a steady flow. Take oil flowing through a pipe for example. That oil is needed everywhere everyday but it only goes about 15 mph through pipes (that number is just off the top of my head, could be a little off). My point is that speed can be counteracted and mitigated via proper logistics.

    Granted, this is a very different topic of discussion than passenger transport.
     
    #13 markabele, Aug 19, 2013
  14. iplug

    iplug Senior Member

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    Yes, I noted above to use the less confusing and more precise term, PMPG(e) instead.

    It would be nice to also have a Top 20 PMPG(e) list like markabele's Top 20 MPGe list. Instead of us guessing at our numbers, if the PiP did the calculation for us, we could have an objective measure.

    In general, if vehicles read out PMPG(e), this might encourage carpooling and create a new category of friendly competition for bragging rights.
     
    #14 iplug, Aug 19, 2013
  15. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    Haha, this might encourage 20 people to load into the back of a pickup truck.
     
    #15 markabele, Aug 19, 2013
  16. iplug

    iplug Senior Member

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    Yeah, that’s one reason why counting only seatbelts in use might work. Then again, if someone really wanted to game the system, one could probably just drive around solo with all seatbelts clicked.
     
    #16 iplug, Aug 19, 2013
  17. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    If car companies are still reluctant to put MPG's on some of their computers then I doubt this will take off. But good thought.
     
    #17 markabele, Aug 19, 2013
  18. CharlesH

    CharlesH CA HOV Decal #5 on former PiP

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    I don't know if it has changed on newer models, but on our 2007 Honda Pilot, there is no way to get a mpg readout short of hooking up an OBD-II device to it. At least that was the consensus at the time on a Pilot forum comparable to PriusChat.
     
    #18 CharlesH, Aug 19, 2013
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