How many miles does full tank display?

Discussion in 'Gen 3 Prius Fuel Economy' started by hellochicken, Jun 9, 2015.

  1. hellochicken

    hellochicken Junior Member

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    So I'm now on my second week with this 2012 Prius and still trying to learn how to roll in it.

    I filled up my very first tank yesterday (dealer gave me a full tank when I bought it) and the miles remaining display said 424 miles after I filled up.
    Does it display 424 on all Priuses by default?

    The first tank gave me right around that many miles before I filled up - the miles remaining display said I had 9 miles left so I got too scared to see if I could go farther.
    But when I filled it, I only filled just under 10 gallons - does that mean there's more miles for me to drive, despite that remaining miles meter?

    And...am I getting pretty bad fuel economy???? I'm so confused with all this Prius technology and number crunching! But I love this Prius so much...
     

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  2. walter Lee

    walter Lee Hypermiling Padawan

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    The Prius on board computer estimates how many miles you have left based on how much gas you have in your tank. However, the estimates are only that - a skilled driver can get more than what the on board computer says is possible. The onboard computer wants you to fill up early to avoid running out of gas -so when there is 0 miles remaining there is normally about 1.5 gallon of gasoline left in the fuel tank. There is no indicator to show that the gas tank is completely empty; however, there is a display to show that all the power to drive the car is coming from the High Voltage (HV) battery pack.... When the Prius runs out of gas it will run on purely electrical power until the HV batteries are drained - but you want to avoid draining the HV batteries if the gas tank is completely empty. . The Prius HV batteries can be drained empty very quickly and if the Prius HV batteries are drained empty after the gas tank is emptied - only a dealership can reboot and recharge the Prus (which is expensive) - you can't refill a no-gas-in-the-gas-tank Prius with gas and run the Prius to recharge the HV battery - and all is forgiven. no - there is a penalty for failure here.

    The real indicator of the achieved fuel efficiency is the HSI display Trip A or Trip B avg mpg estimate which is based on the miles actually driven as recorded by the odometer. The on board Trip A/B MPG estimates are usually optimistic by about 2 mpg, so if it says 48 mpg - when you calculated your fuel efficiency at the pump when you do a fill up - you'll likely get 46 mpg. For example, My trip A odometer says right now I've driven about 500 miles and my estimated mpg is 64 mpg while my remaining miles before empty is about 100 miles. When my remaining miles get to be about 35 miles the single bar on the fuel gauge will start blinking and I will hear for one time only a long beep warning that my fuel is low.
    My third party Linear Logic OBDII Scangauge II xgauge will tell me I have 1.7 gallons of fuel left. . ...If I do a fill up at 600 miles with 0 miles before empty with my estimate mpg still at 64 mpg - my calculate mpg will likely be between 61 to 62 mpg.

    The Prius gets its best fuel efficiency when it is driven over 8 miles or longer than 30 minutes per trip on a dry and sunny day between 60 Fahrenheit degrees and 85 Fahrenheit degrees on a smooth flat road surface at speeds between 22 mph to 52 mph.

    The Prius MPG drops like a rock when it is driven less than 3 miles or less than 10 minutes per trip, driven on wet/snowy days, driven in temperatures under 40 Fahrenheit degrees, driven on rough uneven road surfaces, or driven at speeds over 60 mph.

    The Prius MPG also improves when the driver anticipates and slows down early before doing a complete stop, avoids doing a complete stop by adjusting the Prius' speed, and when accelerations are gradual (no jack rabbit accelerations) - that being said - to achiever higher fuel efficiency on a Prius - the driver needs more time to go from point A to point B - energy efficiency is a compromise between speed and time.

    On hilly terrain - to get better fuel efficiency, a Prius MPG improves if the Prius gets a running start when going uphill and when the driver is skilled at using gravity assisted acceleration to maximize fuel efficiency on the downhill while avoiding excessive speeds to minimize aerodynamic drag . Fuel efficiency solutions gets sort of complex and gray and fuzzy at this point.

    newbie warnings: The Prius 12v battery does not jump start other cars. The Prius isn't good at towing stuff. The Prius MPG is sensitive to tire pressure and type of tire used. The Prius 12v power adapter is really rated for 80w and is not powerful enough to run a 12v portable tire pressure air compresssor. Reports I've read says the Prius needs its transmission fluid changed early to keep the CVT happy ... why? I don't know ! The lower oil change access door can fall off - it needs to be modified so that when the plastic tabs fail it won't fall off. When the Prius is going uphill the fuel gauge can be about 0.2 gallon optimistic and when the Prius is going down hill the fuel gauge can be about 0.2 gallon pessimistic.
     
    #2 walter Lee, Jun 9, 2015
    Last edited: Jun 9, 2015
  3. qdllc

    qdllc Senior Member

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    I'm sure mine reads in the 500+ range. I'll have to look next time I fill up. Each pip on the gas gauge is worth approximately 50 miles, so you have a potential for 600 miles if you average 50 mpg, but the alert to get gas will go off around 500-550 depending on your mpg (I typically get 55-60).
     
  4. The Electric Me

    The Electric Me Go Speed Go!

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    No 424 as a fill up Distance To Empty is NOT a default for all Prius. It seems to me upon fill up The Prius gives you a Distance To Empty or Cruising Range number based on how far you drove on the previous tank. Because my starting Distance To Empty numbers are always close to how far I drove until fill up on the previous tank.

    I typically do use the HSI display with the Trip A chosen below, and I reset Trip A to Zero every time I refill. This will give you an rough idea of your MPG for the tank you are on. It is slightly optimistic but at least on my Prius not too bad.

    My personal observation and adopted urban driving practice in regards to fill ups is to Drive until the last pip flashes, and gives you a single beep upon start up, then change the the display underneath the HSI to display Distance To Empty OR change the MFD display to show the Car Energy Display, which will give you a "Cruising Range" number, which is the same number as Distance To Empty. Then I (without worry or concern) drive until that number reaches Zero. At that point I calmly start looking for a convenient place to refill. The Prius is designed to be optimistic, and my experience has been I can drive to DTE zero, or cruising range zero...and beyond, and still have 1-nearly 2 gallons left. My usual or common driving environment is urban, so finding a gas station is NOT problematic. I would of course as with any vehicle adapt this practice if I was crossing a desert or suddenly driving in an environment where finding a "next" gas station might be a difficult prospect.

    I don't have the desire to test the limits of The Prius, but have found DTE, Cruising Range, to be a safe, good marker as to when to fill up. Usually gives me a good number of miles on the tank, usually is bringing me to fill up, safely and with enough in reserve that at least in a normal urban environment, I wasn't risking running out of gas.

    If you reset one of your trip computers at every fill up, it will give you and exact number of miles driven from fill up to fill up, and if you note how many gallons of gas you are using/buying to fill up, that divided by your number of miles driven calculated by YOU will give you the most accurate MPG per tank.

    First dealer provided tank, first couple of tanks? I wouldn't even sweat MPG too much. Just learn the vehicle and become comfortable driving it. The HSD system does respond to different hypermiling techniques, or just "common sense" economical driving habits, BUT it's also designed to return excellent gas mileage relatively automatically.

    It's perfectly valid and even I think preferable if you are feeling overwhelmed by "number crunching and prius technology" to ignore both. Just drive it as per a normal car. After time passes and you become more and more familiar with the vehicle and the displays, you may discover that the technology that is being displayed isn't so overwhelming at all.

    At first coming from a "regular vehicle", with the multiple displays and choices of display, the Prius can seem daunting. But it really isn't. In fact, some people buy and use scan gauges because they want MORE information than the Prius dash provides.

    My introductory advice, is just enjoy driving your Prius, start calculating MPG per tank, yourself to get the most accurate idea of your MPG, and if you have the time, start reading your owners manual to gain a better specific idea of the information obtainable through different displays on your Prius. But mostly? Just enjoy driving it, and take it one step at a time.
     
    Priusguy78213 likes this.
  5. bisco

    bisco cookie crumbler

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    i filled up yesterday, and it said 639 miles dte. but i got 70+ mpg at the pump.
     
  6. bwilson4web

    bwilson4web i3 and Prime

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    Welcome to the club!
    Nation wide, we're about 2.5% of new car buyers but California is Prius rich.

    One of the first things I did was to take the new car out and run a series of benchmark runs using the tripmeter. I found routes ~10 miles long; set the cruise control at a given speed; reset the trip meter, and measured the MPG as a function of mph. Two runs in opposite direction are averaged so we know what the new car, straight from the dealer does. . . . That way if I have a problem in the future, I can repeat the benchmark and know if it is working as I expect. But then I'm an engineer and measure everything.

    There isn't hardly any 'bad' Prius fuel economy:
    The Prius does reward careful driving:
    • 1st mile of the day - try to take the slowest route, 25 mph, so the engine has a chance to warm-up before putting a load on it. In warmer climates, it can be as short as 1/4th mile.
    • Learn how to 'hide' behind slower traffic - follow, do not tailgate, behind slower traffic so the following traffic will smoothly pass you 'stuck behind the truck' or pickup with a trailer. Sometimes you'll have no choice, don't worry about it. Soon enough you'll find someone to get 'stuck behind.' <GRINS>
    • Try to avoid speeds over 75 mph - and this does not mean a minimum speed of 75 mph! You'll find the Prius really rewards those who can get closest to 65 mph. FYI, I only get 22.5 MPG at 100 mph.
    Mostly enjoy the car, you're in for a treat especially at the gas pump. <WINK>

    Bob Wilson
     
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  7. Ojwasguilty

    Ojwasguilty New Member

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    I agree with the senior members. Your economy isn't bad as I see it, when I first got my 2013 Prius the full tank range was 415 miles, now its more where I like it to be. Hehe.
     

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  8. bisco

    bisco cookie crumbler

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    hellochicken.
     
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