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MPG dropped off after 10k checkup

Discussion in 'Gen 2 Prius Care, Maintenance and Troubleshooting' started by davyk, Sep 30, 2004.

  1. davyk

    davyk New Member

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    I do a regular mix of highway and city driving. For the first 10,000 miles I averaged between 47.5 and 51.2 mpg (real amount- the displayed MPG ranged from 48.2 and 52.5).

    After taking it in for the 10k checkup, my MPG has dropped off to between 42.5 and 46.7 MPG. After putting up with 3,500 miles of this, I called the service department to ask if they might have done something to affect my mileage; they said no. If you look at the 10k list, other than rotating the tires and the oil change, there looks like there is nothing that would affect the mileage.

    One other clue is that the gap between the MPG displayed on the console and the actual MPG has increased significantly. Prior to the 10k check, the difference between the MPG on the display and the actual ranged from .375 to 1.9. since the 10k change the difference has ranged between 1.6 and 6.4 MPG.

    Does anyone have any idea as to what is going on?

    Thanks in advance.
     
    #1 davyk, Sep 30, 2004
  2. efusco

    efusco Moderator Emeritus
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    Have you checked to see if the oil is overfilled? That could easily explain much of the discrepancy. Also, check the tire pressures. I they set where you were running them prior to that check?

    Any other changes in your driving habits.? I'd also just check around under the hood. Any loose hoses? Air filter cover tight?

    The other thing may be the type of oil used. If they inadvertently put in 10W-40 instead of 5W-30 it could have an impact.

    The real answer is that it more than likely has to do with the weather (?increased AC use) driving habits, and non-maintainence related things...but they're worth checking.
     
    #2 efusco, Sep 30, 2004
  3. HTMLSpinnr

    HTMLSpinnr Super Moderator
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    May not be quite as big of a cause, but sometimes the dealer will reset tire pressures. If you kept them high, they will sometimes drop them to the "recommended" pressures. I'd check that too as well as oil.
     
    #3 HTMLSpinnr, Sep 30, 2004
  4. davyk

    davyk New Member

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    Thanks a lot for your responses. I went out a few moments ago to check the tires and the oil levels. The tire pressure on all 4 tires is within a pound of the rating on the driver side panel. The oil level is at full. On the receipt for the 10000 mile checkup it says they used synthetic oil (did not mention the rating).

    The other factors you mentioned (air conditioning, change in driving habits, etc) are, I think, not relevent here. I usually do not use the air conditioning. Some of the highest MPG averages I got occurred during the summer months. It is much cooler now and I do not use the air.

    I do a mix of city and highway driving. I do not have a heavy foot. nor do I do rapid accelerations. Most of the time I am consciously maintaining a light foot on the accelerator.

    I called the service department back and I have an appointment with them tomorrow morning. I have an excel spreadsheet that shows the dramatic reduction in mileage after I brought the car in. I hope they find something.

    I have never achieved the MPG levels that many of you have but was quite happy with my upper 40-low 50 mpgs.

    Dave
     
    #4 davyk, Sep 30, 2004
  5. greengecko

    greengecko Junior Member

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    From driving our 2002, I would say the outside temperature could be the issue, especially if your trips are short. I expected the thermal bottle to have some influence on this, but I haven't seen its influence as expected in our 2004. The batteries operate on a chemical reaction, the warmer they are the more efficient this is. Down to 10 below when they produce NO power and you have to have someone push you out of the driveway (hint, back in if you think it is going down this low, forward is on the engine). In the winter in our 2002 the mileage went down 8 mpg.
     
    #5 greengecko, Oct 9, 2004
  6. richard schumacher

    richard schumacher shortbus driver

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    MPG falls and rises with outside temperature. Plain ol' thermodynamics.
     
    #6 richard schumacher, Oct 11, 2004
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