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Declining MPG in 2004

Discussion in 'Gen 2 Prius Fuel Economy' started by smithBYU85, Aug 7, 2008.

  1. smithBYU85

    smithBYU85 Junior Member

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    I have a 2004 model and am noticing declining FE over the last while. Two summers ago it was getting 55mpg but now Im' stuggling to keep it at 50mpg and it's often as low as 45. I'll try to list the things I do to help FE, please help me identify the areas I'm lacking.

    - Rotate tires (Michelin HydroEdge with about 40k)
    - Change oil every 5k miles
    - Recently changed cabin air filter (I forgot about that one, so it was a while before it was last changed)
    - I keep the tires at 42 psi or above but no higher than 50
    - Recently changed the engine air filter (can't say I'm regular about that either, I keep forgetting about it)
    - I drive with the A/C off as much as possible despite the 90+ temps here
    - I try to excelerate moderatly, without being the one that holds up traffic
    - I use glide techniques

    I tend to enjoy having my windows down while driving on highway speeds and below (60mph on down), does that seriously affect MPG?

    All fluids but oil are original to mfg, none have been changed after 85k miles. If I'm not mistaken the manual says to change them after 100k. Do you think changing those fluids (coolant, transaxle, etc...) would make a big difference?

    I tend to drive 3-4 MPH over the speed limit and my current commute has some minor hills on a highway and the rest is city and some interstate driving. I know I need to excelerate more slowly and I'm working on it (I'm 23, driving slowly isn't so appealing at my age). No, I don't always drive the car like a hybrid, sometimes I just get in and go without thinking my driving habits. I do use the CC as much as possible, I have an injury to my right knee that gets aggravated by holding my foot on the pedels for long periods of time.

    Oh yeah, speaking of the CC, the car never used to waver on the speed, even when driving 75 on I-80 in Wyoming and Utah in the mountains ont he steepest grade, now it does vary a mile or two when going up hill. What can I do about that?

    If there's anyone who can help and feels like responding, I appreciate it. :)
     
    #1 smithBYU85, Aug 7, 2008
  2. john1701a

    john1701a Prius Guru

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    Since you didn't state the current odometer reading... YES!

    At 100k, my coolant & transaxle fluid changes seemed to deliver a small improvement.


    Says who? As an advocate of brisk acceleration, my 48 MPG in the northland of E10, slow is something I cannot relate to nor see the need for.

    .
     
    #2 john1701a, Aug 7, 2008
  3. efusco

    efusco Moderator Emeritus
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    He said he's at 85k miles John.
     
    #3 efusco, Aug 7, 2008
  4. john1701a

    john1701a Prius Guru

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    Reading it again, I still get the impression miles are higher from the word "after" and the reference to 100k.

    Wanna wager on what it really is?

    .
     
    #4 john1701a, Aug 7, 2008
  5. F8L

    F8L Protecting Habitat & AG Lands

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    5 internet credits the milage is 85k. :p


    Could you be experiencing the symptoms of an ailing battery? Ahve you had the Aux battery checked? If that checke dout good have you thought about getting the hybrid battery checked?
     
    #5 F8L, Aug 7, 2008
  6. samiam

    samiam Antipodean Prius Poster

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    I blame global warming ;-)
     
    #6 samiam, Aug 7, 2008
  7. efusco

    efusco Moderator Emeritus
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    Sure, I'll wager.....

    Here's my rewrite of the sentence as I read it....

    "All fluids but oil are original to mfg, none have been changed yet after 85k miles on the ODO. If I'm not mistaken the manual says to change them after 100k. Do you think changing those fluids (coolant, transaxle, etc...) would make a big difference if I changed them a little sooner than that?"

    Regardless who's right about the mileage I don't think it will have any direct impact on FE if he changes the fluids.
     
    #7 efusco, Aug 7, 2008
  8. paprius4030

    paprius4030 My first Prius

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    I think maybe there's more damn corn in the gas this year that screws up the mileage
     
    #8 paprius4030, Aug 7, 2008
  9. smithBYU85

    smithBYU85 Junior Member

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    Sorry guys, I was away from my computer for a while. Efusco and F8L are right, I just hit 85k last week, sorry for the poor wording. I checked the 12v a few months ago after seriously draining it and it had charged back to a full 12v but it is the original battery. I have not checked the HV battery yet.

    I wouldn't think that the fluid change would make that much of a difference but with a car this special, who knows?

    I don't mean accelerate so slowly as to make other drivers mad at me, but to keep from really revving the engine. I haven't decided if a slow acceleration or a brisk acceleration to the speed limit is the best, I'm still evaluating that.
     
    #9 smithBYU85, Aug 7, 2008
  10. smithBYU85

    smithBYU85 Junior Member

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    Could be, I know that 10% garbage drops my MPG by about 4-5 miles. I try to buy gas that doesn't have ethanol in it and unless it's unadvertised I don't think I am. I double check when I fill up again. Are they supposed to advertise it at the pump that it has or may have ethanol in the gas?
     
    #10 smithBYU85, Aug 8, 2008
  11. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Before changing my transaxle oil, I did a series of 'hill rolling tests' in cold weather and found the first change made a significant improvement. If you plan to change the transaxle oil, see if you can find a very shallow hill near your home that you can do a "roll down" test over a week. You want the start to be such that your car comes to a stop by itself, using "N" and the engine off _IF_ _SAFE_.

    Get the transaxle oil changed and repeat the hill roll down test and share the results.

    I have not been able to do a 'warmed', hill rolling test. Even the old oil, when the car was warmed, would reach the end with significant velocity. In my case, the temperatures were around freezing.

    Also, what are your front and rear wheel alignment numbers? Rough roads or stress can throw the toe and camber off enough to increase tire drag. Also, what tire size, make and model, are you running now?

    Rolling resistance is bad news because it robs performance all of the time. That is why my first efforts have and remain focused on reducing rolling resistance.

    Bob Wilson
     
    #11 bwilson4web, Aug 8, 2008
  12. mikepaul

    mikepaul Senior Member

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    That 'revving' thing does eat into your MPGs, but normally a brisk takeoff doesn't do that if your drive battery is happy.

    Ever since it got HOT here, I've had battery issues where it goes pink on me almost daily. It's an odd cycle: when it's pink the engine runs more (POOR acceleration since the electric motor won't help) followed by not-quick recharging until everything is normal again. Then later, when going up more than a few hills, I'll notice that the battery is low again like it 'forgot' to maintain charging. I'm wondering if the vent in the backseat needs cleaning or something, to get more of the A/C down there to help the battery...
     
    #12 mikepaul, Aug 8, 2008
  13. smithBYU85

    smithBYU85 Junior Member

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    I waited to post so I could try to find those numbers, the dealer gave them to me when I changed my oil a few weeks ago but I can't find the paper that they gave me. If I find them I'll get back with you. I'm about to move out of my apartment so I have stuff in lots of places while I pack.
     
    #13 smithBYU85, Aug 9, 2008
  14. richard schumacher

    richard schumacher shortbus driver

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    BZZT! *Do* use the A/C, because it also cools the battery system. If you feel too warm then so does the battery. When the battery gets too hot it will throttle itself, and that reduces MPGs.
     
    #14 richard schumacher, Aug 14, 2008
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