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Fuel Economy Questionnaire - Is my experience reasonable?

Discussion in 'Gen 2 Prius Fuel Economy' started by Tomel51, Jul 4, 2010.

  1. Tomel51

    Tomel51 Junior Member

    Joined:
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    Location:
    Virginia
    Vehicle:
    2009 Prius
    Following are my responses to the questionnaire on mileage. I've averaged 41 mpg over life of vehicle (15,693 miles), getting a few mph less in the winter and getting better on two long trips I've taken (1800 miles @ 65 mph average - 48 mpg, 220 miles @ 55 mph average - 52 mpg).

    Basically, I'd like to know whether my experience seems reasonable based on my normal driving parameters. Seems like I'm averaging about 10 mpg less than most posters on Prius Chat.


    Mileage Questionnaire Responses

    - Have you read This Thead Yet? Yes

    - What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations). 41 MPG, manual calcuation over life of vehicle (15,693 miles)

    - What fuel economy are you expecting and why? Mid 40's or better, based on Consmer Report testing. 50+ mpg based on looking at Prius Chat member experiences.

    - What are the approximate outside air temps? MidAtlantic Region (High 80's summer, 30's winter)

    - How long are your trips? 5 miles to 10 miles

    - How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving? Suburban driving. 35 mph to 45 mph. Lights about every 1/2 mile. Traffic rarely backs up, speed can generally be maintained.

    - What region/state are you in? (if you haven't set your location in your profile) Metro Richmond, Va

    - What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.). Gentle hills

    - Is your oil overfilled? (i.e. above the full mark on the dipstick). No, filled to full mark.

    How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here). Car was purchased new 2/2009.

    Have you had your alignment checked? Yes. Any pulling or abnormal tire wear? No.

    - Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15). Yes, factory.

    - What are your tire pressures? 35 psi

    - Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.)2006 Honda Civic. 26 mpg.

    - How are you trying to drive (e.g. trying to stay in electric only? No, not normally. ) and how hard are you braking? Try to brake gently most of the time.

    - Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on? No.

    - Are you driving using D or B mode? D mode.

    - HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to? Yes, 70 degrees

    - If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute? Not Applicable
     
  2. cycledrum

    cycledrum PSOCSOASP

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    Hope this helps

     
  3. cycledrum

    cycledrum PSOCSOASP

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    FWIW, I measured tire tread depths on driver's side front tire (40 PSI cold) -

    middle - 7/32", inner 7/32"

    outer 6/32"

    Doesn't seem the tire is 'overinflated' which I think would be indicated by a low middle reading. I thing outer tread depths tend to run bit lower as I've seen outer edges of tires wear out more quickly.

    I don't plan to go over 40 PSI in fronts as the ride is firmer at higher pressures.

    Maybe inflating your tires will help.

    Are you checking tires before driving, in the morning, IOW, cold?
     
  4. Rokeby

    Rokeby Member

    Joined:
    Jan 21, 2008
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    Location:
    Ballamer, Merlin
    Vehicle:
    2008 Prius
    I'll say that your MPGs are about what I'd expect at the speeds that
    you're driving. At 35-45 MPH you could get 55-60 MPG, but...

    From the info you provided, I'd say that four conditions are keeping
    you from seeing FE/MPG closer to 50:

    * Mostly short trips -- it takes the car 3-5 miles to get fully warmed up
    and into its most efficient mode of operation. (-3-8 MPG)

    * Relatively frequent slow-downs/stops.

    * Tire pressure -- can be raised to 42F/40R without impacting tire life,
    though ride quality suffers. (-3-5 MPG)

    *Use of air conditioning -- every degree cooler than outside air temps
    costs you MPGs. The air co runs off the HV battery so its hard to see its
    FE impact. Ultimately the ICE is running more to keep the HV battery
    within the HSD's preferred limits, especially in slow/stop-and-go
    driving. (-3-5MPG)
    Sorry about this, but a 75 deg setting will make a noticeable difference.

    Remember that driving the car as an EV -- using yellow arrows only --
    is the most inefficient way to move the car due the conversion losses
    as power goes from the ICE via MG1 to the HV battery, then from the
    HV battery to the drive wheels via MG2(?).
     
  5. bisco

    bisco cookie crumbler

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    i don't think it's reasonable. i drive 7 miles to work each way. in decent weather, mild hills, 30-40 mph, 2 miles at 55 mph, i can get 55 mpg without even trying. keep working on it, hopefully you'll find the answer. this is just not a 45 mpg car unless you're driving like a.j. foyt in colorado in the winter. all the best!:)
     
  6. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Three
    I agree with almost everything Rokeby says, but I see fuel economy climb for the fist 15 miles of my trips, then level out.

    I average 47 in fall and spring, 42 in summer and winter.
     
  7. Bob.H

    Bob.H Junior Member

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    I have been logging fuel and mileage since we bought our used 2008 in April 2009. We have traveled 17250 miles and received a calculated average MPG of 41.9

    I consistently get 3-4 MPG better when I drive vs. my wife and she puts the majority of miles on it. My wife makes short trips of one block to 4 miles for most of her miles with the AC on AUTO. I also found it running parked in the garage all night a few times.

    Bob
     
  8. JimboK

    JimboK One owner, low mileage

    Joined:
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    Location:
    Chesterfield, VA
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    I'm a lifelong Richmond area resident and I know the area well. If you can give me some details of your specific routes, including street names, time of day, starting points and destinations, I can give you some feedback. Or link a Google map with your route(s).

    And if you're interested, I can also do a hands-on driving clinic with you to help you optimize mileage.
     
  9. Ophbalance

    Ophbalance Member

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    Something else to consider... I live and drive mostly in NC, but went through VA two weeks back. I do not know what they thin your fuel out with up there, but I could NOT get the same mileage that I typically get on the fuel I ended up getting while in VA. The trip up averaged 59 MPG, the trip back was 57... which is odd as the winds favored the return leg, and it should have been more downhill. I was extremely happy to be through that tank.