How can I be sure my low mileage, isn't car related?

Discussion in 'Gen 2 Prius Fuel Economy' started by nimrodgrl, Aug 20, 2008.

  1. nimrodgrl

    nimrodgrl New Member

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    I have read all the things you can do to gain more miles per gallon, but has anyone had another issue with the car or engine that caused a decline in feul efficiency? Or has anyone experienced a true Prius "Lemon?"

    I have a 2004 and have had better gas mileage until the last few months. Nothing has changed and I check my tires, etc...

    Your thoughts or experience please. :help:
     
  2. brick

    brick Active Member

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    Can you give us some more detail? How long you have had the car, how you drive it, what the weather has been like, any and all things that you might have done/have happened to the car in recent memory, etc. would all be useful.

    Having just bought a Prius and getting low mileage is one thing, usually attributable to either the driver or conditions, or occasionally measurement error. That's pretty easy to sort out. A car that suddenly loses mileage is another matter.
     
  3. efusco

    efusco Moderator Emeritus
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    What was your prior MPG, what is it now? Have you checked the air filter, have you had the alignment checked, have you tried a familiar route to see what the difference in MPG is. My usual commute I can get 70-75mpg in good weather, 55-60 in cold weather. Any trip significantly below those numbers without explaination (air conditioning, bad traffic, etc.) is cause to look for an explaination.
     
  4. tochatihu

    tochatihu Senior Member

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    A car swap would be a straightforward way to answer this question. Do you have any friends with Prius?
     
  5. unigeezer

    unigeezer Member

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    Only 70-75? Why is your mileage so low? I routinely get 85-110mpg driving 70-80mph, uphill, with the ac blasting at full.
     
  6. richard schumacher

    richard schumacher shortbus driver

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    After four years it's not a lemon. The problem is the heat; your MPGs will improve as the temperature drops. The same thing happens with mine in Dallas.

    Note that you *should* use the A/C in hot weather because it keeps the battery system cool.
     
  7. efusco

    efusco Moderator Emeritus
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    I forgot to mention I'm towing a 30 ft. camper trailer!:fear:
     
  8. unigeezer

    unigeezer Member

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    I figured either that or you were driving with the brake fully depressed! I drive mine with my 2 tons of gold bars in the back.:rolleyes:
     
  9. dwreed3rd

    dwreed3rd New Member

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    Nimrodgrl: You in the middle of Prius country USA. Between the members here on PC and your contacts out there, you should be able to find a really expert Prius service. If it's that big of a difference and you can't pin point any changes that would affect mileage, since it's a 2004, it may be time for a good once over by a reputable Prius service shop. One with a dynamometer. It may be worth the ounce of prevention. Any good Prius certified service shop should be able to evaluate your car, especially since it does not seem to be an intermittant problem. And if they exist anywhere you should have one around your area. Sometimes I think CA must have half of the Prius' in the US. If they give it a clean bill of health, then you can focus on driving habits. We could speculate til the cows come home and not help you. That's my suggestion.
    That plus 2 cents will get you, well! gee! nothing anymore.
     
  10. nimrodgrl

    nimrodgrl New Member

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    You guys are great. Thank you for responding.

    I have owned the car since 2004. I drive slower than I used to, keep the tires at the correct pressure and conserve my breaking. I don’t expect 60 or 70 mpg. Several months ago I was getting 48 mpg. and have had about that kind of mileage. You should know that I live in a very hilly place so avoiding hills is impossible. So over the last few months I have only been getting 38 mpg.

    Efusco has some good suggestions I will check out (e.g. air filter and alignment). It has been warmer but I can’t imagine my mileage would drop that much because of that. I rarely use my air conditioning.

    Another good suggestion from dwreed3rd is to see how well others in my direct area with a Prius are doing with their mpg.
     
  11. Celtic Blue

    Celtic Blue New Member

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    I could be mistaken, but my understanding is that if you are letting it get too warm in the car, the traction battery might be running too warm as well. This could make the control system reluctant to charge the battery and/or discharge the battery when it should.

    If what I just said is a load of hooey then I am sure (or hope) that someone more knowledgable will correct my statements.

    I don't think it sounds like you are purposefully avoidng using AC and "driving like a Spartan", but if you are it might be counterproductive.

    Another ventilation related issue is to make sure you don't have anything obstructing the battery's vent into the cabin (beside the right side passenger seat.) Doing so will make the battery run warm and prevent it from being used efficiently.

    Is the car garaged or is it sitting in the sun? (And most importantly did this change with regard to previous years.) I expect a hot interior (and therefore a hot battery) to get worse mileage on short trips in the summer.

    If you can think of anything that changed at about the same time you noticed the mileage drop, it might help...even if there appears to be no reasonable link at first.
     
  12. richard schumacher

    richard schumacher shortbus driver

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    Have you been getting all of the scheduled maintenance?
     
  13. Celtic Blue

    Celtic Blue New Member

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    When was the last time the 12 V battery was checked or changed? I've seen some anecdotes about marginal 12 V batteries giving poor mileage. On other vehicles my batteries always show their age either when the weather first gets hot, or when it first gets cold--never during mild weather, it is the extremes that produce a stress test that fails batteries.
     
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