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New (to me) Prius Questions

Discussion in 'Gen 2 Prius Main Forum' started by cgm55082, May 5, 2013.

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  1. cgm55082

    cgm55082 Junior Member

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    I recently bought an extremely well maintained 2006 Prius with 102,000 miles (have maintenance records from Toyota dealership). The car is in excellent condition and runs perfectly, but I'm really disappointed with MPG -- 41 MPG.

    Here's what I have done to try to improve mileage:

    1) Immediately took car to Toyota dealership for inspection -- passed with flying colors.
    2) I changed the oil to synthetic 0-20W, per Toyota, and only use 87 octane gas.
    3) I regularly practice pulse and glide techniques. Most of my driving is a commute of 35 miles each way, 70 percent of which is at 60 mph and 30 percent city streets. I live in an area that is flat, dry and about 68 degrees year round.
    4) I have cleaned the MAF sensor, per PriusChat, and replaced air filter with OEM.
    5) I have checked the auxiliary battery via the in-car display. Registers 12.3 volts after sitting overnight, 10.9 volts under full load (HID lights on, both defrosters on and blower on). I think this means it's okay.
    6) Have checked the traction battery fan to make sure it was clean -- it was.
    7) Transaxle fluid was changed at Toyota dealership 15,000 miles ago.
    8) The car does have new tires, BF Goodrich Advantage T/A in OEM size. I read new tires can decrease mileage somewhat, but I've also inflated the tires to 44 front and 42 rear -- did not noticeably improve mileage.
    9) The only other thing I can think of is to change the spark plugs, but I doubt that will make much difference in MPG. The car runs excellently and has no signs of aging plugs.

    Is there anything else I can do to help increase my mileage? I'm disappointed as it seems most people are getting at least 7 to 10 mpg better than I am.
     
    #1 cgm55082, May 5, 2013
  2. bisco

    bisco cookie crumbler

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    welcome to priuschat! how old is the 12 volt?
     
    #2 bisco, May 5, 2013
  3. bisco

    bisco cookie crumbler

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    where do you live? is it hilly?
     
    #3 bisco, May 5, 2013
  4. Britprius

    Britprius Senior Member

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    I have a strong feeling the problem is your tyres. Hopefully F8L will bring his US tyre knowledge in on this, but I am reasonably sure the rolling resistance of those tyres is very poor. The Prius requires low rolling (RR) tyres to achieve good mpg.

    John (Britprius)
     
    #4 Britprius, May 5, 2013
    HaroldW likes this.
  5. Britprius

    Britprius Senior Member

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    Just found the UK Goodrich TA tyre, and it's RR is rated at E on a scale of A to G, A being the best so this tyre is not suitable for the Prius. New tyres will also require a brake in period during which the mpg will be lower.

    John (Britprius)
     
    #5 Britprius, May 5, 2013
  6. cgm55082

    cgm55082 Junior Member

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    I live in the central coast region of California. There are some hills on my commute, but nothing dramatic, just a couple of rolling hills. Mostly my driving is on flat roads.

    The auxiliary battery was replaced in January of 2010. It has 30,000 miles on it. Not sure how to interpret the test of it, but it seems like it's in the normal range.

    I'm stumped...
     
    #6 cgm55082, May 5, 2013
  7. bisco

    bisco cookie crumbler

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    how many tanks have you gone through and are you figuring mileage based on fill up and miles driven? agree with brit pri if they aren't lrr tyres, it can cost you.
     
    #7 bisco, May 5, 2013
  8. cgm55082

    cgm55082 Junior Member

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    John, thanks for posting the rolling resistance of the tire. Do you know what the MPG differences would be between a tire that is say an A on the rolling resistance scale versus a G? I ask because I've read of several other Prius owners who have the same tires as me, but still have much better MPG than I do.
     
    #8 cgm55082, May 5, 2013
  9. cgm55082

    cgm55082 Junior Member

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    Bisco, I only have three tanks worth of mileage on the car. So far I've only taken mileage measurements from the car display. I've read the display actually tends to over calculate your mileage, so there's a good chance my actual mileage is only in the mid to high 30s. Waiting for a couple more fill ups to calculate it by hand, because I want to average out the differences that could be caused by the fuel bladder.
     
    #9 cgm55082, May 5, 2013
  10. bisco

    bisco cookie crumbler

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    good idea. when you refiil, you might want to take a long trip on back roads 30-40mph without many stops, just to see what the average shows. no reason not to get 50 plus doing that.
     
    #10 bisco, May 5, 2013
  11. Britprius

    Britprius Senior Member

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    The EU ratings system states the variation of fuel consumption between two grades of tyre (eg A to B) is between
    2.5% to 5%, so the difference between A to G could be 15% to 30%. You would also need to add the loss caused by new tyre brake in. In the US at the moment the best tyres you can buy are rated at B for RR

    John (Britprius)
     
    #11 Britprius, May 5, 2013
  12. Britprius

    Britprius Senior Member

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    The tyres you have on your car could easily be loosing you 10% on your mpg and I honestly suspect it is higher than this. F8L is the US tyre guru on PC. I would suggest you post about your tyres in the section "LRR tyres current list" in the yellow box at the top of the economy section of the gen2 Prius for a reasonably quick answer from him.

    John (Britprius)
     
    #12 Britprius, May 5, 2013
  13. GoesStation

    GoesStation Junior Member

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    Did you reset the fuel mileage when you started driving this car? The displayed mileage is the cumulative total since the last reset. If the previous owner was drove with less care for economy and the calculator hasn't been reset for a long time, the displayed mileage doesn't reflect your own history.
     
    #13 GoesStation, May 5, 2013
  14. cgm55082

    cgm55082 Junior Member

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    I did the reset right when I purchased the car.
     
    #14 cgm55082, May 5, 2013
  15. cgm55082

    cgm55082 Junior Member

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    What are most people with a gen II Prius averaging? I'm just trying to figure how far off my mileage is.
     
    #15 cgm55082, May 5, 2013
  16. Britprius

    Britprius Senior Member

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    In the UK 60mpg is the figure to head for. In the US as your gallons are smaller I think 50mpg is realistic. Higher figures are attainable for both countries, but there are many variables to contentend with possibly temperature being the main one. In the UK 600 miles to the tank should be attainable, but in the US this depends on the amount of fuel you can get in the tank with the bladder, the UK does not have this.

    John (Britprius)
     
    #16 Britprius, May 5, 2013
  17. desmondlee

    desmondlee Member

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    i have a 2007, 98500 miles, tires were changed at 50,000 - currently getting 48 - 50 miles per gallon.
    has always been somewhere in that range
     
    #17 desmondlee, May 5, 2013
  18. wjtracy

    wjtracy Senior Member

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    We avg 46-47. Speed is one thing. 60 mpg should be OK but if its really 70+ there will be drop off.

    The other thing is usually 12v battery. Even though it was replaced, sitting around at dealership could run down and lose effectiveness. I do not have it handy, but you will see posted here how to use your display to test the 12v battery. Do this test to see how you are doing.

    I am not familiar with the tires. OEM tire is GY Integrity which is LRR. You want LRR tires. Go to TireRack.com and see recommended Prius tires and see how your tires measure up in the comments. Also many posts here and F8L is expert. Gen2 we do not have some of the tire choices that Gen3 has.
     
    #18 wjtracy, May 5, 2013
  19. richard schumacher

    richard schumacher shortbus driver

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    Uh, you don't ever shift into "B", right? Just checking.

    Do you use the parking brake? It could be dragging.
     
    #19 richard schumacher, May 5, 2013
  20. nh7o

    nh7o Off grid since 1980

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    On the 12V battery: if it is bad enough, it can eat up significant power as the charger tries to bring it up to voltage. Make sure that the ICE shuts off on those glides and down hill sections. If the engine runs too much, trying to keep a failing 12V alive, it will eat some MPG. Yours is close to the end.

    Lots of short trips can reduce MPG.

    Also, have the alignment checked. I just had mine done and I notice the difference when gliding. The Prius coasts really well when everything is right.

    I get 49 MPG on hilly terrain, with Michelin LRR tires.
     
    #20 nh7o, May 5, 2013
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