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Current tank 40.7mpg so far, best is 46.7 2010 Prius 112K miles

Discussion in 'Gen 3 Prius Fuel Economy' started by thordehr, Sep 5, 2013.

  1. thordehr

    thordehr Member

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    !! CORRECTION: BEST IS ONLY 43.4MPG !!​
    ​
    ​
    - Have you read This Thead Yet?​

    Yes.

    - What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations)​

    Last tank so far has been 40.7mpg Of the three fill ups I have since the car was new to me, my best was my first at 43.4mpg. This has been through the on board trip computer.
    The car has 112,000 miles on it. I've driven a total of 755miles.

    - What fuel economy are you expecting and why?​

    High 40's to low 50's. Based on EPA city MPG of 51 and highway of 48 MPG.

    Fuel Economy of the 2010 Toyota Prius

    - What are the approximate outside air temps?​

    80's to 90's.

    - How long are your trips?​

    Daily trips to the gym of 0.6 miles one way and to work 2-3 times a week of 15.0 miles one way.

    How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here)​

    My assumption is that it is the original battery. Voltage is 11.7 volts... That's right now, not overnight. It might be too low and be the low mpg culprit? I could see it causing some mpg loss due to recharging the battery more often than normal, but not this much...

    Have you had your alignment checked? Any pulling or abnormal tire wear?​

    Alignment has not been checked. Does not seem to pull and tire wear seems even.

    - How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving?​

    Going to work is mostly highway but it is Los Angeles highway so sometimes up to 75mph, other times a lower speed not quite stop and go traffic. Trip computer is telling me that the overall average speed I've been doing is 25 mph.

    - What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.)​

    Fairly flat, not very hilly at all.

    - What are your tire pressures?​

    40psi all round.

    - Is your oil overfilled? (i.e. above the full mark on the dipstick)​

    No, just below full.

    - Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.)​

    Was so bad I didn't calculate it. Probably 10-15 mpg.

    - What region/state are you in? (if you haven't set your location)​

    Los Angeles

    - How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking?​

    Trying to do coast when possible and minimize hard braking as to not max out the regen bar on the meter.

    - What modes are you using, if any? "normal", EV, power, eco? ​

    Normal.

    - Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on?​

    No, but gym trips are short and low speed. Work trips are low speed for 5-10 minutes before I reach the highway.

    - Are you driving using D or B mode?​

    D

    - HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to?​

    Using AC, auto mode, recirc, 74-73.

    - Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15).​

    Stock 15" rims.
    Tires ARE near worn out and are due to be replaced. 3mm front 2mm rear.
    Michelin
    Weatherwise II
    P195/65R15 M+S

    Tires aren't anything special and may be a factor hurting my mpg. Do not seem to be a fuel saver tire and were probably bought at Sears.
    Them being worn out may lead to less tread squirm and a harder tire so them being worn out may not be hurting me that much. OR the low tread means there is more rubber in contact and could hurt mpg some....


    - If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute?​

    I have done a full service on it since owning it.
    Proper fluids and items for following items.
    Oil change
    Changed PSD oil
    Changed spark plugs
    Air filter was inspected and looks clean.
    HV battery condition was checked with the traction monitor and the battery seems to be in good condition with all cells looking equal:
    Traction Battery Monitor results and information interpreted. | PriusChat


    So, the only things I seems I can do to improve mpg from this point is to get new LRR tires on it and a new 12V battery in it. Maybe verify the alignment too.
    That doesn't seem enough to make up 10 MPG or more though, does it?
     
    #1 thordehr, Sep 5, 2013
  2. bisco

    bisco cookie crumbler

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    great job on the details! low 40's might be expected at those highway speeds and the short trip to the gym because the ice can't warm up. non lrr tyres can cost you 3-5 mpg. definitely research the battery condition some more. some 10's came with weak batteries. a/c will cost you a bit. don't forget, epa is a controlled test and YMMV. that being said, under the right conditions, is is possible to do much better as well. all the best!(y)
     
    #2 bisco, Sep 5, 2013
  3. thordehr

    thordehr Member

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    Going to check the battery again after a normal day of driving (15 miles) and then the next morning to get an accurate voltage reading.
    How much can a low 12V battery cost you?
    Any ideas anyone?
     
    #3 thordehr, Sep 5, 2013
  4. bisco

    bisco cookie crumbler

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    a lot, because the ice has to keep coming on to recharge it. or should i say, the hv battery has to recharge it and the ice has to recharge that.
     
    #4 bisco, Sep 5, 2013
  5. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    I would have advised you against a Prius based on the length of your commute.
    considering a Prius | PriusChat

    In some failure modes, the inverter can spend all it's time trying to charge a battery that just can't get to 12 volts, it never quits trying.
    Weird stuff happening? MPGs dropping? Test The Battery | PriusChat
    Optima DS46B24R Optima battery direct fit replacement for Prius 2004 + , Prius V & Plug-in Prius with Instructions

    LRR tires may help over time, any new tire displays poorer gas mileage than it will when older.
    Energy Saver A/S | Michelin Tires
     
    #5 JimboPalmer, Sep 5, 2013
  6. jhinsc

    jhinsc Senior Member

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    Not sure you can expect much more than you're getting. On your daily trips to the gym, the ICE is barely getting warm before you stop. Living in LA with it crazy traffic patterns doesn't help either. You are getting much better mileage than your previous car - were you even close to EPA on that one?
     
    #6 jhinsc, Sep 5, 2013
  7. wjtracy

    wjtracy Senior Member

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    I never heard of those tires for a Prius, and I agree with you it may be part of problem.
    I am thinking about trying the Michelin A/S which Jimbo just mentioned.
    Also obviously short trips are part of the problem. I wonder if it makes any sense to limp to the gym on EV mode (if that is even possible).
    Why not try a Optima Yellow Top new 12v battery?

    In your case (if you are REALLY trying to improve MPG) you may need to study in depth that short daily trip to the gym (maybe with SCAN guage) to see how to do that with the least fuel consumption. Does the following make any sense?: leave car on while in Gym so you would get home at ~50 MPG. This is brainstorm I don't know if that is advisable.

    Longer term this is where a PiP fits in nicely. You could do EV mode to gym and never see the low MPG from the cold engine.
     
    #7 wjtracy, Sep 5, 2013
  8. thordehr

    thordehr Member

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    I could get close to EPA on my previous car but had to drive it very gingerly, it was close to 500HP and too much fun on the skinny pedal.

    Optima DS46B24R Optima battery direct fit replacement for Prius 2004 + , Prius V & Plug-in Prius with Instructions

    Shows a different Optima than when I look up a battery online:

    8171-767 Battery - 2010 to 2012 L4 1.8L 325CCA Hybrid - Prius - Toyota - Car and Truck - Batteries Plus

    Wonder which one is correct.

    I'll have to look at that closer when I check the battery again in a few days.

    Tire are inevitable and will be on by or at my next oil change at 120,000.
     
    #8 thordehr, Sep 5, 2013
  9. fuzzy1

    fuzzy1 Senior Member

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    ​
    That does seem low for having been driven in the last few hours, but not quite so bad for Prius mpg if it has been sitting overnight. And while being a bit low, it is not clear if that is the aging battery itself, or an artifact of the short trips not giving it enough charge time. Do you have a 12V battery charger available to top it off as a test?
    Worn tires shouldn't hurt mpg at all. Non-LRR tires will hurt, and new tires will hurt temporarily until broken in. But since the car was not outfitted with brand new but lousy-mpg tires just before you acquired it, you now have opportunity to make your own choice of good tires. Many used car buyers get stuck with poor tires too new to be worth changing.
    That's right, these should make up only part of that 10 mpg. The short trip warmup penalty, and the 75 mph on the highway, make up another chunk.

    The auto AC may also eat up another chunk, especially on the short trips to the gym. If you can comfortably turn down the fan speed, raise the temperature to the high 70s, and point the driver vents directly at you while closing the far side passenger vent, you may be able to reduce the AC fuel cost.

    Do you reset one of the trip meters every morning? This can help provide very rapid feedback about driving conditions and style. It will highlight the warmup penalty, showing a hideously low MPG at the start and continuously improving as warmup proceeds and distance increases. The mid-trip numbers don't matter, only the final number at the end of the day really matters.

    Then practice your hypermiling style, using whatever methods comfortably fit your traffic conditions. There is plenty of advice here, and over at Uncle Wayne's place at CleanMPG.com.
     
    #9 fuzzy1, Sep 6, 2013
  10. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Batteries Plus just uses an internal part number rather than Optima's part number.

     
    #10 JimboPalmer, Sep 6, 2013
  11. bwilson4web

    bwilson4web BMW i3 and Model 3

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    Just a thought, could you bike or walk to the gym?

    I live in Huntsville AL and fully understand there are places where a bike is impractical even for short trips. Las Vegas comes to mind.

    Bob Wilson
     
    #11 bwilson4web, Sep 6, 2013
  12. ursle

    ursle Gas miser

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    Check the in cabin air filter, if it's clogged, it will require more energy to push air.
    You need a new 12v, but in the meantime, unhook the 12v for a few minutes, then hook it back up, it would be excellent to trickle charge it to full load while unhooked, but, the car's a digital device, and digital devices love to be unplugged, periodically, then try a mileage test.
     
    #12 ursle, Sep 6, 2013
  13. retired4999

    retired4999 Prius driver since 2005

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    A friend of mine just put new tires on his 2011 prius and He did not believe me on tires, He put Uniroyal tiger paws on and his gas mileage has droped 8-10 mpg and He sure is complaining now! He was at about 61 mpg and now He is having a hard time keeping 52 mpg.

    See if you can stand having your air cond. set at about 78-80 degrees. It does make a big difference! 1-2 mpg.
    Short trips is a killer fo mpg. Hard to fix this one. Highway speed kills mpg to, 65-70 mph would be better but this is hard to fix also.

    These things may get you close to 50 mpg.
     
    #13 retired4999, Sep 6, 2013
  14. thordehr

    thordehr Member

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    Tires, a closer look at the cabin filter and battery are on tap.
     
    #14 thordehr, Sep 7, 2013
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