Temperature/Trip Length Matter!

Discussion in 'Gen 2 Prius Fuel Economy' started by Ken S, Mar 21, 2014.

  1. Ken S

    Ken S Member

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    My 2005 Prius is now nine years old and has about 90,000 miles on it. My experience over those years with the car has been very good from a reliability standpoint. The only major issue was the coolant pump failing on me and a couple of dead batteries (lights left on).

    My fuel mileage experience has been so-so when based on the EPA estimates.

    First, the one real difference between my car and most 2005 Prius is that it has some 17" wheels that the Toyota dealer "included" as must extras in order to purchase the vehicle (there was a very long wait for the car back then). I'm sure the bigger heavier wheel causes lower fuel mileage.

    I keep my tires at 38/40 PSI.

    Until 2013 I lived in Southeast Florida and for much of that time had no commute and drove under 7,000 miles a year. When I went out it was either to run errands or for trips of roughly 30 minutes or so in length. My A/C was set to 77 (Auto). I got 42 - 45 MPG.

    We then moved and we started driving our sons to school which meant two trips of about 25 miles each with a period of sitting in a pickup line each day. If the temperate was over 80 our MPG would sink to 40 at best. During the months when the temperature would be consistently in the low 70s or cooler (it doesn't really go below 60 in SE Florida) I would get 45+. It seemed to be almost entirely A/C dependent.

    This past Fall we moved to Martha's Vineyard and for the most part my "commute has become two pickups at school which consist of drive 5 minutes, park, drive 5 minutes back. The terrain here is flat for the most part, but not quite as flat as Florida.

    When the weather is in the 50 - 75 range the fuel mileage has been in the mid 40s.

    When the temperature drops into the 30s and below I'm struggling to stay above 35. (I keep the temperature on auto with it set to 66 when it's cold). I do use the front and rear defrosters when necessary. The car is kept in a garage.

    I've had the car checked extensively by a trusted mechanic and there are no error codes, alignment and wheel balance is dead on and when I put the car in EV mode only I get almost the exact same distance out of the battery as I always have (1.5 - 2 miles).

    While not a hyper-miler, I do drive with MPG in mind.

    Anyway, for me the two biggest factors in MPG on the Prius:

    1. A/C & Heater use - those systems seem to suck the life out of MPG
    2. Length of trip - Anything below 15 minutes and MPG suffers
     
  2. tanglefoot

    tanglefoot Whee!

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    As they say in the old country, "Ya, sure, ya'betcha!"

    It's tough to find factors that affect fuel economy more than temperature and trip length.

    I assume you have an aftermarket EV button? Be very cautious and conservative in its use. It can shorten the life of the traction battery and reduce MPG.

    I feel that not using auto mode on the climate control is less energy taxing than controlling it manually and miserly. Auto mode tends to run the A/C compressor frequently, even when it may not be needed. I also feel like it helps MPG to drive the first few minutes with the climate control off.

    Do you have any pictures of the car on its 17s? I don't think I've seen one come off the lot with 17s.
     
  3. bisco

    bisco cookie crumbler

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    of course, your driving style may have a lot to do with it. but things like 17" wheels (LRR tyres?) and ev buttons have more to do with it than short trips and hvac use.
     
  4. Ken S

    Ken S Member

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    I put the EV mode button in two months ago just to play with. Have probably used it less than a handful of times.
     
  5. Ken S

    Ken S Member

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    The EV mode button has nothing to do with it as it has only been in place a couple of months and is rarely used.

    The wheels have been there since day one so while they may effect the overall mileage they have nothing to do with the differences in efficiency since I've owned the vehicle.
     
  6. Ken S

    Ken S Member

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    View attachment 63102 View attachment 63103 IMAG0338.jpg
    Here you go...

    My car also had leather seats which wasn't offered by Toyota factory in 2005. However, when you buy a Toyota in the Southeast they all go through a Toyota distributor who actually changes the standard options packages available. The wheels, tinting and a pinstripe were dealer add-ons that were not optional if you wanted a Prius back then at any of the dealers in SE Florida.

    Here's some pictures of the wheels and seats. Sorry, they're not great snapped them with my phone while it was in the garage. The winter here has also made my poor car filthier than it ever was down South.

    IMAG0338.jpg IMAG0337.jpg IMAG0339.jpg

    Oh, driving a black car in SE Florida without the A/C on even for a few miles isn't really something a sane person does. However, when it was cool enough in the mornings I could do it and would get somewhere around 47 - 48mpg if I was careful.

    I expect my next daily vehicle here will be some sort of EV or EV/Charger. I'd like a Tesla X, but that won't happen as long as I'm married. It would be great if Toyota would release that Rav 4 EV nationwide though.
     
  7. bisco

    bisco cookie crumbler

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    i can't offer much else but my own experience. with my '04 and '08, and a 7 mile commute each way to work, i got 55mpg in the winter, 60 in the summer and 65 when i didn't need a/c.
     
  8. Ken S

    Ken S Member

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    I don't doubt you, but I have never come close to 55 MPG...I used to think there was something wrong with my car until the EPA adjusted their estimates to about 45 which was much closer to my experience.
     
  9. bisco

    bisco cookie crumbler

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    yeah, it's all about terrain and speed and stop and go and so many factors. i'm fortunate to have a very prius friendly ride.:)
     
  10. tanglefoot

    tanglefoot Whee!

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    Thanks for the pics. That's a nice-looking wheel/tire combo. They likely reduce MPG though, not necessarily due to weight (those alloys look pretty light) but maybe due to width (what is the section width of those tires, BTW?) and that those low-profile tires probably have a pretty soft rubber compound.

    If you are interested in maximizing MPG, you might look for a second set of wheels (15x6) with some fast-rolling 185/65R15s on them with plenty of air pressure.

    It's fine to use the A/C when it's hot...it likely even helps prevent damage to the HV pack. With the low frontal drag coefficient of the Prius, MPG over about 40 mph is likely better with the windows up and the A/C on than with the windows down and no A/C.
     
  11. Ken S

    Ken S Member

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    The wheels are made by or for Toyota as they are/were pretty much a standard (TRD) item in every Toyota dealership where I used to live. I thought of getting another set of wheels, but even if it improved fuel mileage 10% it wouldn't make sense financially...especially with the car rolling into it's 10th birthday.

    I've always gone with low RR tires and keep the pressure high. I'll post the tire size when my wife returns with the car later. I believe they're 7" wide and take a P215/45R17.

     
  12. nh7o

    nh7o Off grid since 1980

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    Ken, are those MPG numbers taken from the MFD, or are they calculated? Have you checked the odometer to make sure the miles are accurately measured? Larger diameter wheels will offset this a bit.
     
  13. Ken S

    Ken S Member

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    I use both...My father taught me to always record fuel vs. odometer. It's generally pretty close to the MFD.
    While the wheels are bigger the tires are low profile. I once measured them against a regular Prius and the overall diameter is almost exactly the same.

    The odometer appears to be very close. I measured it several times on a highway with mileage markers and have also run the speedometer against a police laser gun (he's a friend) and it was accurate.

    What's most striking to me was the difference between Florida and Mass. Moving to a cold climate dropped fuel mileage almost 20%. Once it gets warmer it'll be interesting to see if it comes back up...although the 2 mile trips with a stop in between are probably never going to do well MPG wise.

     
  14. engerysaver

    engerysaver Real Senior Member

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    In cold weather; look into grill blocking to increase your MPG!!:)
    Their are several threads on the subject; and it works.
     
  15. Ken S

    Ken S Member

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    Thanks, I'm going to do that. I started searching here and I think I'll go with the pipe insulation method. Just got to find a post with the right size to use.

     
  16. Ken S

    Ken S Member

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    After searching through a lot of threads I can't seem to find a consensus on what type or size pipe insulation to use? Is 1/2" best and at least 36" lengths with vertical cuts to fit around the vertical supports in the grill?

    I'm probably only going to block the bottom. It'll be interesting to see how much it helps on these short drives.
     
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