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What decreases mileage

Discussion in 'Prius c Fuel Economy' started by RocMills, Aug 24, 2012.

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  1. RocMills

    RocMills Active Member

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    I know that running the a/c will gobble up your mileage, but what about things like the radio, the media (USB) player, the fan without a/c, the bluetooth?

    Trying to get a handle on why some days the exact same trip costs 38 cents and other days it costs 66 cents. Obviously, traffic is also a great impact.
     
    #1 RocMills, Aug 24, 2012
  2. Ashley7

    Ashley7 Active Member

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    Traffic, weather, how long you let the engine warm up, exactly how you accelerate from each stop, etc, etc. With short trips especially, it'll vary a ton based on lots of different things. I don't imagine using media affects it all that much, but I'd be curious to know otherwise. There are so many different variables that it would be hard to pinpoint exactly what's making the difference in a given trip. (An interesting thread topic, nonetheless!)

    My commute is 3.4 miles. My phone is always connected via BlueTooth, and I'm always listening to my mp3 player via Aux jack. The mileage I get has varied from 40 mpg to 74 mpg.
     
    #2 Ashley7, Aug 24, 2012
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  3. RocMills

    RocMills Active Member

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    I always let the car warm up until the ICE stops running, I never put the car in gear before that.

    The particular trip I'm referring to is only about 9 miles in each direction, with the car shut off for maybe 2-3 minutes (if that) between stopping and starting up again. My bluetooth is always connected, but not always in use. But I certainly listen to music from one device or the other all the time.

    I realize that the traffic patterns are probably the biggest impact, but since I know that a/c impacts mileage, I was just wondering if any of the other shiny-bits in the car did so as well.
     
    #3 RocMills, Aug 24, 2012
  4. Ryephile

    Ryephile The Technophile

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    FYI, there's no reason to do this, especially knowing our cars run as fully-stoichiometric Atkinson cycle. Get in the car and start moving immediately. In fact, don't even turn the car on until you're actually ready to go. Even in the winter. Having the car sitting there wasting fuel doesn't make sense. The car will warm up much quicker if it's under mild load, like driving out of a subdivision for example.

    The audio system takes relatively little power unless you have it full blast all the time. Big electrical draws are the A/C, steering, rear window defroster, and lights [esp. both low and high beams]. As such, your best economy is going to be going steady-speed perfectly straight down a straight road in moderate temperature low-humidity daytime with no DRL, no audio, & no vent fan.
     
    #4 Ryephile, Aug 24, 2012
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  5. RocMills

    RocMills Active Member

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    Thanks, Rye!

    I have been using DRL so I will stop that. Defrost seems to work quickly enough (and not be needed very often), so I won't worry about that. Can't live without the audio, and except when our temperatures get into triple digits I prefer to have windows down over using a/c anyway.
     
    #5 RocMills, Aug 24, 2012
  6. Ashley7

    Ashley7 Active Member

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    I've been leaving my DRLs on too. Do they really make much of a difference?
     
    #6 Ashley7, Aug 24, 2012
  7. fuzzy1

    fuzzy1 Senior Member

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    No, keep using them for safety. The energy cost of LED DRLs is tiny compared to having the whole lighting system (high or low beams) turned on, and even those are not energy expensive enough to forgo their safety benefit in the absence of the LED version.
     
    #7 fuzzy1, Aug 24, 2012
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  8. AWDstylez

    AWDstylez 500hp to 99hp

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    No, but every little bit counts and DRL's are the most pointless thing since unsliced bread.
     
    #8 AWDstylez, Aug 24, 2012
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  9. RocMills

    RocMills Active Member

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    Hmmm... I can see both points of view regarding the DRL. Perhaps I will experiment, as best I can, to see if there really is any noticeable difference in drive cost with and without the DRL. Though I do prefer to err on the side of safety.
     
    #9 RocMills, Aug 24, 2012
  10. F8L

    F8L Protecting Habitat & AG Lands

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    Roc, just keep them on. The power usage is tiny and will not have a detectable affect on fuel economy outside of a lab environment. I keep mine all the time and still get 65-70mpg (indicated) in my GenIII.
     
    #10 F8L, Aug 24, 2012
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  11. RocMills

    RocMills Active Member

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    Thanks, F8L, that's reassuring. I will continue to leave them on, just need to remind the two others who sometimes drive the car to stop turning them off!
     
    #11 RocMills, Aug 24, 2012
  12. F8L

    F8L Protecting Habitat & AG Lands

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    If it helps in any way to make your car more visible to other drivers AND look cool then I think it's a good thing. ;)

    You know my opinion on the A/C hit to fuel economy.
     
    #12 F8L, Aug 24, 2012
  13. RocMills

    RocMills Active Member

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    Odd... I see the first sentence in your post, but I don't see the second one until I quote it. Actually, I'm so overwhelmed by everything here I'm not certain of your a/c opinion... but I've experimented with that myself and the difference was staggering. However, when the temperature hits 112 and the car has been outside all day, I can't make it with out running the a/c at least long enough to cool down the interior.
     
    #13 RocMills, Aug 24, 2012
  14. F8L

    F8L Protecting Habitat & AG Lands

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    #14 F8L, Aug 24, 2012
  15. cwerdna

    cwerdna Senior Member

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    Gas Mileage Tips might help the OP.

    I also wouldn't sit around warming up the ICE until it stops. You're getting 0 mpg that whole time and I don't think enough of a load is placed on the ICE to do that much charging into the HV battery.

    AC is definitely a big power consumer. Lights aren't really. Bluetooth and stereo aren't either. If one gets a ScanGauge II and can monitor amps going in/out of the HV battery (there's definitely an XGauge for Gen 2), one can get a better idea of the big/small draws.

    Trip length and cool down time between trips are probably the biggest contributor. Short trips will kill your mileage and a long cool down between each doesn't help. Too high a speed will hurt too.
     
    #15 cwerdna, Aug 24, 2012
  16. RocMills

    RocMills Active Member

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    Thanks for the link. I think I instinctively do most of that already. Unfortunately, there is no shaded place for me to park either at home or at work. My windows are tinted as dark as the law will allow, and I am using a windshield sunshade (though not a nice one customized for the C, as i am not overly fond of those large folding ones - no convenient place to keep them when they aren't in the window). Car is always in Eco mode. And I usually do keep the windows cracked for fresh air even if I'm running the a/c. What I don't do is operate the a/c at any setting other than as low as it will go (temperature-wise) but I only run that fan at about half speed or less.
     
    #16 RocMills, Aug 24, 2012
  17. RocMills

    RocMills Active Member

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    cwerdna,

    I will cease the ICE warmup immediately, and I've never been a speed demon behind the wheel of a real car. Unfortunately, there really isn't anything I can do about trip lengths or time between trips. I already plan my multiple-stop trips so that I visit the farthest destination first. However, 4 times a day I am required to take a trip that is merely 9.5 to 9.7 miles long, though heavy city traffic with lots of lights, and one pair of those trips leaves the car off for only a minute or two. Also, I don't think there is a flat stretch of road in this town that's more than a mile long... every street here is a series of inclines, small ups and downs.
     
    #17 RocMills, Aug 24, 2012
  18. cwerdna

    cwerdna Senior Member

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    Yeah, I never sit around warming up the engine, but I recall some folks saying that some hypermilers do sit around warming up their engines. I don't recall their logic behind it, but it's not something I'd do.
     
    #18 cwerdna, Aug 24, 2012
  19. Minglehill Prius

    Minglehill Prius Junior Member

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    Because of the following post in "Gen III 2010+ Prius Technical Discussion" I have understood it is better to sit while the engine does it's 50 sec. warm up. A test over 4 tanks trying to keep all things the same - 2 tanks: always waiting for the engine to quit - then 2 tanks: not waiting for the engine to quit - seemed to indicate a 3 mpg improvement when I sit and wait till it quits. VERY unrealable test I know.

    So I would like to know if you feel the following warmup stage info is wrong. Especially "Prius can not use the engine power when you drive. Prius is driven by battery power and the battery is discharged."

    Gen3 warming up stages
    Read more: http://priuschat.com/threads/gen3-warming-up-stages.76501/#ixzz24VvMzAw1
     
    #19 Minglehill Prius, Aug 24, 2012
  20. RocMills

    RocMills Active Member

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    Minglehill,

    My first question would be... is that information relevant to the C or to the larger Prius? Also, I don't do Celsius, so I don't know what 40 degrees Celsius works out to in Fahrenheit... but this is the Vegas desert, and we only get chill temperatures in the very heart of winter. When the car has been sitting in the direct 110 degree sun for 8 hours, I don't think I have to worry about the coolant temperature being too low.
     
    #20 RocMills, Aug 24, 2012
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