Black Betty MPG

Discussion in 'Gen 3 Prius Fuel Economy' started by myfirsteverprius12, Apr 14, 2012.

  1. myfirsteverprius12

    myfirsteverprius12 Just getting started

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    Hi Prius Chat Members, I just wanted to start by saying thanks to everyone for their help. Wth is this guy talking about? you may wonder... Well, let me begin.

    I decided to get a 2012 Prius II after doing some extensive research and budgeting . Let me give you some pre-requisites. I drive about 130 miles a day, 120 of those miles are highway, and about 10 are short distances between stop signs and getting on and off the highway. The WORST driving conditions it seems for any car, but that's why I chose the 2012 Prius, rated at 50 city / 40 highway.

    I WAS driving a 2006 Scion xB that normally got around 28 mpg, but when I accelerated slowly, stuck to 60 mph on the highway, and coasted in neutral down all the hills I came across, I was averaging about 36.

    So in comes April 9, 2012 and out comes Black Betty. My Black 2012 Prius II bought from Longo Toyota in Los Angeles, CA. First new car I've ever bought and I am ecstatic.

    I've also picked up a ScanGauge which I will refer to later in this post as I have some questions about it. Ok so let me post some stats now that I've filled her up for the first time (a painful yet joyous occasion after seeing 489 miles on the ODO). My best in the Scion was 353.

    First Fill Up: 8-490 miles

    Trips Recorded:

    Work - Home 57.0 miles 59.7 mpg 51 mph (avg) 4.10
    Home - Gym 9.1 miles 92.3 mpg 17 mph (avg) 4.10
    Home - Work 63.8 miles 54.4 mpg 56 mph (avg) 4.11
    Work - Post Office 2.3 miles 51.1 mpg 15 mph (avg) 4.11
    Work - Home 56.8 miles 56.7 mpg 54 mph (avg) 4.11
    Home - Work 64.0 miles 54.0 mpg 50 mph (avg) 4.12

    So according to the Heads up Display for Trip A (which encompassed all of my "full tank" supplied by the deal) I got 487.2 miles on one tank. The ODO read 490 total miles. I took delivery with 9 miles on it and again a "full tank" of gas. I reiterate this because when I filled up with 11.687 gallons of 87 octane Arco Brand Gasoline and did the math, I calculated 41.68mpg which seems a little skewed because of the extra gas I had in there compared to when it was delivered. I hope this improves the next fill up because I will again be topping off.

    So the HUD says 53.7mpg and my actual is 41.68mpg. Test results? Inconclusive this far. I also have a fuelly account to help me track my MPG and I use an iPhone app called GasCuddy to help me track it along with service reminders, tire pressure recordings, etc. I'm super nerding out, and why not? This car was made for it!

    So here comes my questions. I've done my research about the ScanGauge, and after mastering how to actually spell the word, I'm on to some more technical questions! Right now I'm not using the trip function, I'm more interested in the Gauge Functionality of the device. I have it set to show me RPM, MPH, MPG, and Water Temperature.

    I have read some posts somewhere here on PC about having the IGN/TPS showing, but when I was playing around with I couldn't make sense of what was going on. I know that the RPM drops to 0 when I'm going under 46 and the SOC is good, and i'm gliding blah blah blah...what I'm more interested in is the 46mph+ range like on the freeway.

    I understand that when I'm in Glide mode, and the HSI is non existent on the screen, I've backed off the accelerator and got back on it just a little bit so I know I'm gliding, if I was going under 46 it'd be easier to notice, hence; why I bought the ScanGauge. And I know that the engine's pistons have to move in order to protect the electric motor from spinning too fast. So my question is how do you know (besides that infinite mpg do hickey) particularly on the ScanGauge that there is no gas being sent to the the engine, that the pistons are only moving in order to protect the electric motor. I know I've read it somewhere but I honestly can't remember. Maybe someone can help point me in the right direction.

    I apologize for the lengthy post and any grammatical errors I may have made, but I plan on utilizing this site a lot more now that I am a member and I have a place to bounce my ideas off of. Thanks for all your help!!!

    John
     
  2. spiderman

    spiderman wretched

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    Welcome aboard John! Hope you don't mind, I didn't read all the post. :)

    Bam Balamb.
     
  3. myfirsteverprius12

    myfirsteverprius12 Just getting started

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    spiderman,

    How could I be mad? You were the first one to come to my rescue.

    Bam a lam a lam!!!!
     
  4. spiderman

    spiderman wretched

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  5. SuperchargedMR2

    SuperchargedMR2 Diehard Rams Fan

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    It will take a few tanks of gas to calculate the SG so that it's really accurate for MPG. Why do you show MPH? Seems like a waste. On mine I show...

    1. Ave MPG
    2. Instant MPG
    3. Coolant Temp
    4. RPM

    The amount you were off on your first tank was a lot. You sure ran the tank really low on fuel too.

    Congrats on your new Prius & welcome to PriusChat. :D
     
  6. fuzzy1

    fuzzy1 Senior Member

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    High instant MPG ( 4 digits when moving faster than 20 mph, high 3 digits at lower speeds) or low GPH (gallons per hour) are good enough.

    The later often gets stuck at 0.02 gph instead of zero, but that doesn't seem to be real. For the short time I had GPH up, it seemed to never be under 0.2 gph when except when the ICE was off, or in transition.
     
  7. direstraits71

    direstraits71 Member

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    Your tank was not as full when you got your car as you filled it at the Arco station. Don't worry until you've done at least 3 tanks or more and divided the miles traveled by the gallons burned. The Gen3 mileage displayed by the car is known to be a bit optimistic also. Search the forum and you'll find discussion of that.
     
  8. Sabby

    Sabby Active Member

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    This is worth reading from Hobbits site

    HSI

    Reading this along with your scan gauge should help you.

    Make sure you go through the calibration routine when you next fill your tank on the scan gauge.
     
  9. GreenJuice

    GreenJuice Active Member

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    Welcome to Prius world. I can see you are going to have fun!

    To add to fuzzy1's comments:
    SG will need to be set up and calibrated to get the most accurate figures. If you set your fuel cut TPS, you might get GPH=0.01 reading more often. This means, and others have observed, that SG can't actually show fuel cut and therefore estimates MPG in this situation, giving the range of results listed by fuzzy1.

    RPM below 1000 can be another indication of fuel cut.

    I'm guessing you use water temperature because it is a useful guide for understanding the car's behaviour during warmup. Next up, you will find that SOC explains a lot of the behaviour of the car, too.

    I use HV battery amps as an indicator of the basic energy flow (like a basal metabolic rate!), around 1 - 3 amps depending on what configuration of items you have on like lights, A/C, fan speed, etc. This helps me control how much HV 'assist' I choose to give to a glide.
     
  10. alfon

    alfon Senior Member

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    When you filled up Black Betty you probably filled it
    to the maximum which is the top of the filler neck.

    When the dealer fills more than likely they just
    fill to first auto click.

    I know for a fact after the first auto click you can still
    pour in at least 2 more gallons of fuel. The Prius
    2010-2012 all have solid fuel tank that will hold a max
    fuel capacity of about 13.5 gallons when filled to top
    of filler neck.
     
  11. revhigh

    revhigh MPG Enthusiast

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    Not in my car. When my fuel pump shuts off I could get MAX another .4 gallons in. I also have seroius doubts as to whether the Prius holds 13.5 gallons when it's specced at 11.9. You should never fill a car 'to the top of the filler neck' ... it can damage the evaporative canister ..... at least that's what some people say. Either way ... it just makes no sense to do it.


    I put my filler nozzle into the car, hook it on the first spring loop, use the same gas station and pump every time, fill at the slowest speed, and when it shuts off, that's it ... I don't round up, or do any extra filling. That's the only way to fill it consistently every time.

    Why would you run the car so far out of gas ? I never understood why people do that. When the last pip starts blinking ... fill the car up the next chance you get ... it doesn't change your mileage at all to continue driving just to see 500 miles on a tank.

    REV