Heavy load = higher MPG!?!?!?

Discussion in 'Prius c Main Forum' started by Mikey The Mailman, Mar 23, 2013.

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  1. Mikey The Mailman

    Mikey The Mailman Delivering snail mail for you ;-)

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    I'm confused!

    My car now has 9,300 miles since July. I normally drive 25 miles each way to/from work with 95% highways.

    After work 2 days ago, I stopped by Home Depot & loaded 16, 12'X12" concrete step stones in my trunk (protected by thick old blanket) and drove 10 miles home, sure it feels heavier but I noticed 99mpg for couple miles even with gas running. by the time I got home it was 74 mpg!!!!

    Yesterday after work, I did the same picking up the last 16 of same, drove home the same way giving me 76 mpg.

    Today, it was back to normal 46mpg trip (cold morning) and 55mpg (cooler afternoon)

    What gives????? Makes me think I should leave that in my C all the time LOL (No way!!!)

    And yeah, I shouldn't load that much in the first place :whistle:
     
    #1 Mikey The Mailman, Mar 23, 2013
  2. cwerdna

    cwerdna Senior Member

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    #2 cwerdna, Mar 24, 2013
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  3. Mikey The Mailman

    Mikey The Mailman Delivering snail mail for you ;-)

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    Elevation from home depot (20 feet) and my home is 43 feet

    I've frequently stopped at stores to pick up food, and while engine was warm, I never saw what I saw in the last 2 days with very heavy load!!!
     
    #3 Mikey The Mailman, Mar 24, 2013
  4. ztanos

    ztanos All-around Geek!

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    Was the weather warmer than usual?
     
    #4 ztanos, Mar 24, 2013
  5. fuzzy1

    fuzzy1 Senior Member

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    To really test it, stop by Home Depot on your next commute home in similarly warm dry weather, resetting the MPG gauge but going home without picking up any load.

    What MPG do you get? By excluding the engine warmup portion of the commute, it will beat the usual 55 mpg from work. I'm guessing it will match or beat your loaded HD trips.
     
    #5 fuzzy1, Mar 24, 2013
  6. Mikey The Mailman

    Mikey The Mailman Delivering snail mail for you ;-)

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    It was cooler weather while the first time I picked up a load was a windy day then the next day with cooler and calm winds
     
    #6 Mikey The Mailman, Mar 25, 2013
  7. bisco

    bisco cookie crumbler

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    sounds like you need to stop at the donut shop every morning!:p
     
    #7 bisco, Mar 25, 2013
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  8. Mikey The Mailman

    Mikey The Mailman Delivering snail mail for you ;-)

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    o_O :LOL:
     
    #8 Mikey The Mailman, Mar 25, 2013
  9. RRxing

    RRxing Senior Member

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    More weight = Car sits lower = Better aerodynamics = +20 mpg increase! Simple! :rolleyes:
     
    #9 RRxing, Mar 25, 2013
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  10. DKTVAV

    DKTVAV Active Member

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    To OP, did you test this way yet?

    If you want to be fair wait the same amount of buying stuffs in the car and then drive home.
     
    #10 DKTVAV, Mar 25, 2013
  11. Mikey The Mailman

    Mikey The Mailman Delivering snail mail for you ;-)

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    Yes, I did today on my way home...I stopped by chipotle which is in the same shopping center as Home Depot...it's normal and the temperature was around the same! (n)
     
    #11 Mikey The Mailman, Mar 25, 2013
  12. ztanos

    ztanos All-around Geek!

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    and... ?
     
    #12 ztanos, Mar 26, 2013
  13. DKTVAV

    DKTVAV Active Member

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    I believe he's saying "it's normal": not higher MPG with heavy load.
     
    #13 DKTVAV, Mar 26, 2013
  14. Mikey The Mailman

    Mikey The Mailman Delivering snail mail for you ;-)

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    What I'm saying is on every day daily driving my mpg reminds the same UNTIL these 2 days I loaded up 16 square foot concrete step stones which heavy thus boosted my MPG to the mid-70's! THAT'S what got me confused as WHY would heavy load cause higher MPG than empty (except me, of course) load!?!? Ever since these 2 days of heavy load, it's back to normal to mid-45 to low 50's (due to cooler weather here)
     
    #14 Mikey The Mailman, Mar 27, 2013
  15. jgilliam1955

    jgilliam1955 Sometime your just gotta cry! 2013 Prius 4.

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    Haven't you ever heard of the "heavy load MPG fairy?"
     
    #15 jgilliam1955, Mar 29, 2013
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  16. Mikey The Mailman

    Mikey The Mailman Delivering snail mail for you ;-)

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    :ROFLMAO:
     
    #16 Mikey The Mailman, Mar 29, 2013
  17. mahout

    mahout Active Member

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    I have a sneaking suspecion that youchanged the angle of the car with the extra weight thus thinking it had more gas than it did.The weight also drops the car which has less aero drag and thus you let it think you were getting more mpg. And of course there's not more downhill is there? More weeight means more work to speed up and slow down so should mean less mpg, too.
     
    #17 mahout, Apr 13, 2013
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  18. vindicator

    vindicator Junior Member

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    I've read that two reasons the C does not get not substantially better mileage than the hatchback is that 1) it's shorter, so the Cd (coeff. of drag) is higher and 2) it lacks adequate mass to capitalize on regen during coast down. The concrete blocks may have temporarily alleviated that issue.
     
    #18 vindicator, Apr 17, 2013
  19. ztanos

    ztanos All-around Geek!

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    Except that he says he lives 20ft uphill elevation wise, from the Home Depot.
     
    #19 ztanos, Apr 17, 2013
  20. vindicator

    vindicator Junior Member

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    If it's a couple of miles between Home Depot and his house, elevation difference is negligible and can be ignored.
     
    #20 vindicator, Apr 17, 2013
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