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Discussion in 'Gen 3 Prius Fuel Economy' started by Susan4ET, Jul 4, 2015.

  1. SageBrush

    SageBrush Senior Member

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    I don't think so.
     
  2. bisco

    bisco cookie crumbler

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    did you have anything afetermarket installed? or dealer add on?
     
  3. Susan4ET

    Susan4ET Member

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    Sooo, I think I ran across the possible problem. There is a display setting where you can set your mpg and for whatever reason when tinkering with that I left it set to 20.0 mpg. Is it possible that the car computer was 'weighing' that into the calculation keeping the mpg low?

    Anyway, I reset this mpg value to 50.0; reset/confirmed settings of everything else; fueled the car and set off on a 50 mile round trip not exceeding 55 mph once. As soon as I pulled out of the station I knew things were better. By the time I reached the halfway turnaround point Trip A read ~61 mpg. When I reached home it was ~57 mpg and the final trip readout when I turned the car off said ~55 mpg. So right now I think its working better then the EPA estimate. Since I don't make this sort of trip often it will be interesting to see if my city/highway daily driving stays above 50 mpg or not. If I drive 'well' with some basic hypermiling I should never see < 45 mpg again.

    Now all that's left is to discover what that funny wire is hooked up to the 12 V battery hold down strap? And what that mpg display setting does?
     
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  4. SageBrush

    SageBrush Senior Member

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    I have never encountered the setting you speak of, and I have idea what it does. Can you post a couple of photos from the screen ? What steps did you take to reach that setting ?

    I doubt your hypothesis of 'weighting' because you said in your OP that without 'hypermiling' your tank average would drop. That implies driving for more than a while at less than 34 MPG. Your 50 mile jaunt result however sounds pretty reasonable.
     
    #24 SageBrush, Jul 4, 2015
    Last edited: Jul 4, 2015
  5. DoubleDAZ

    DoubleDAZ Senior Member

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    My guess is that setting is for comparison purposes just like the price entry for cost saving calculations. I'd bet there is a display that shows you how much above or below that "goal" your last trip was. Pg 234 of the 2014 Owner's Manual shows how to set it, but I can't find the explanation of what it's used for. I set mine to the 24.5 mpg our old van got, but I've never found where it tells me anything, though I admit I haven't looked at the monthly consumption report, etc.

    Edit: I just looked at the report and didn't see anything related to the mpg I entered.
     
    #25 DoubleDAZ, Jul 4, 2015
    Last edited: Jul 4, 2015
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  6. bwilson4web

    bwilson4web BMW i3 and Model 3

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    This is what I measured in May 2009:
    [​IMG]

    I'm glad you ran the test since this is how we know what the car does "new." It gives us a benchmark to diagnose future problems.

    GOOD LUCK!
    Bob Wilson
     
  7. breakfast

    breakfast Active Member

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    Glad to see your mpg's are great in the real world. The 2015's are doing just fine on this board - see my fuelly below with standard air pressure and 99% driving in "normal" mode :)
     
  8. bisco

    bisco cookie crumbler

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    if when 'resetting confirming everything else', you reset the trip meter, than that was your problem. you were being weighted down by low starting average from the dealer. it's difficult to bring the average up much on a single tank. glad you're all good!(y)
     
  9. CR94

    CR94 Senior Member

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    It connects to a temperature sensor, so the all-knowing computer will know the temperature of the battery's environment.

    ... and congratulations!
     
  10. cyclopathic

    cyclopathic Senior Member

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    if it is 2015 it has to be under warranty.

    From what I've seen so far many Prii had alignment issues from the factory. My C was re-aligned at 5K service, and front had over 1/2" toe-in on both sides; way to much. After fix MPG went up, and then slightly grew up when tires broke in.

    Also due to tight tolerances, first few hundred MPG really bad, and it will be improving all the way to 1st oil change at 10K.

    Check tire pressure, that is another buzz killer.
     
  11. DoubleDAZ

    DoubleDAZ Senior Member

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    The actual computed mpg for my first fill-up was 7.6 mpg higher than the CONS display. That led me to believe they topped off the tank without resetting Trip A after driving the car over from a dealer on the other side of town. When we bought the car, there were no Blizzard Pearls available anywhere in Phoenix, but another dealer had one coming the following week. So they traded one of their Grays for mine and when it came in they drove the Gray over and swapped cars. The funny thing is that when the salesman stopped to top off the Gray, another car backed into it at the service station. Not sure how they worked things out, but we've got our BP and that's all that matters to us. :)
     
  12. Susan4ET

    Susan4ET Member

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    When I had the PiP I would set off to get gas locally on battery only and then do errands as long as I could within EV only range. Showed excellent mileage until I had to make one of those longer trips or the engine just had to run. Tough to do in winter needing the heater. :)
     
  13. AzWxGuy

    AzWxGuy Weather Guy

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    Assuming fairly consistent design in all of the Generation III vehicles, the outside air temperature sensor is located lower center of the bottom air intake in front of the radiator. If you look straight down through the opening where the hood safety catch is, you can see it down there. And the dashboard plug you mention is probably the night-day optical sensor that was on the left side of the dash near the inside bottom of the windshield on the Generation II. IIRC it does something with the air conditioning schedule which doesn't have to be as aggressive at night. Not sure if it is involved in the automatic headlight system. Someone more knowledgeable will likely chime in.
     
  14. KennyGS

    KennyGS Senior Member

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    That's what I thought its main purpose was.
     
  15. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Was there a problem with the PiP that you traded it in?

    There were reports of Oregon going with an alternate taxing system on cars like the PIP. Did anything ever come of it beyond the prototype system?

    Bob Wilson
     
  16. Okinawa

    Okinawa Senior Member

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    It's too soon to panic. Just drive the car for a period of time and don't worry about it for now. Check your tire pressure before you drive it in the morning.
     
  17. Susan4ET

    Susan4ET Member

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    No problems with the PiP but I had to give it up because lease was coming due and Toyota had their deals going with no PiPs on the lot; I hoped to save a little money with a new standard Prius lease; was told that although I could wait for a new PiP there was no guarantee there would be any sales special for it; was also told or learned with no confirmation that the PiP production was being phased out because of the hydrogen car coming out, which I doubt I will be able to afford right off the bat anyway...

    Oregon is just starting a pilot program where certain vehicles (I sure hope that will include heavy trucks too one day) will track miles driven in Oregon and that that is what will be taxed rather than a tax at the pump which is otherwise where the PiP especially and Priuses in general have quite an advantage. We'll see how this goes and how other states deal with the same problem. I know little else at this point, am not participating at this point, and have lots of questions.

    BTW, on my recent test the weather has been around 95 F so the A/C was running as needed to hold 72 inside the car the whole trip. In fact I always leave it enabled to run automatically when needed. It doesn't look like A/C really has a significant effect on mpg up here. Maybe much worse effects in the Southwest or driving through Death Valley?
     
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  18. SageBrush

    SageBrush Senior Member

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    Well now, that tidbit of information would have been welcome in your first post.

    Cooling in a Prius is probably the most efficient of any car, but nothing is free. The first 5 minutes of cooling, when the system is bringing the cabin temperature and humidity to the level you set can be quite a drain; keeping the cabin at that setting is usually much easier on the system. Personally, I do not cool down the car if I am only going for a short trip for the above reasons.

    There has been a lot of useful discussion in the forum how to minimize the energy consumption of A/C in the summer if you are interested. For Oregon start with:
    1. Always set a sun-block on the windshield. Takes 30 seconds to place or pull down
    2. Keep windows cracked for ventilation. In Oregon you probably would want to install rain guards.
     
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  19. Susan4ET

    Susan4ET Member

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    Is there a graph for 'average' miles per gallon in stop and go city driving speeds under 45 mph? Now that I'm driving around the city and off the main highway (no more constant 55 mph speed tests) when I finish a brief trip around town of 5 or 10 miles and turn the car off it might show an average of 33 mpg. The graph might show both extremes--hypermiling expertise vs making no hypermiling efforts?

    I've wondered why 'B' can't work automatically--especially when accelerating and I've forgotten once again to put it back into 'D'? For stop and go do you just leave braking on?
     
  20. fuzzy1

    fuzzy1 Senior Member

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    No, because there is no meaningful 'average' stop-and-go situation. The shorter the trip, the worse the MPG because the fuel penalties for initially warming the engine, and initially cooling the cabin, are spread over fewer miles.

    In flat areas, DON'T USE 'B'. EVER.

    'B' is strictly for long downhill descents that could overheat the brakes. In flat areas, it produces no change while accelerating, but costs fuel at other times. Using 'B' incorrectly won't hurt the car itself, only the MPG.
     
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