1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Odd gas mileage data

Discussion in 'Gen 2 Prius Fuel Economy' started by paulagoodfellow, Jun 16, 2008.

  1. paulagoodfellow

    paulagoodfellow Junior Member

    Joined:
    Sep 1, 2007
    19
    1
    0
    My Prius had about 10, 200 miles on it when I left Friday for a trip from our home near San Diego to Palo Alto this past weekend. The town I live in is very hilly, so I've been averaging around 43 mpg and was interested to see if it would be higher on the trip. (I rented a Prius in Utah last month, but stayed in the valleys, mostly on long trips, and averaged 49.5 with no real attempts to keep mpg high.) On this trip, on the way up to PA, we were getting around 46 mpg according to the display, but when we filled up, it took exactly 7.0 gallons when the pump shut off. We'd gone 397 miles since the last fillup, so something was obviously off. I don't know if my husband messed anything up, but he was so surprised that he kept trying to put more gas in it, with the pump repeatedly shutting off. On the way home, the display showed us getting about 47 MPG, and then we stopped to get gas at 330 miles, just to avoid getting gas in LA. I"m not sure how many squares it showed left, at least three. That time he put 10.2 gallons in. That's a bit scary! What could have been going on there? And now, we've gone another 150 miles, averaging 47 mpg and still have all the squares.
     
  2. paulagoodfellow

    paulagoodfellow Junior Member

    Joined:
    Sep 1, 2007
    19
    1
    0
    I realize it's a bit confusing the way I wrote the mileage. It's 10,200. And the distance from our house to Stanford is about 525 miles.
     
  3. qbee42

    qbee42 My other car is a boat

    Joined:
    Mar 2, 2006
    18,058
    3,075
    7
    Location:
    Northern Michigan
    Vehicle:
    2006 Prius
    You can't calculate Prius gas mileage from the gas pump. The useful gas tank capacity of the U.S. model of the Prius varies from tank to tank, depending on temperature, age, and gas pump settings. There is enough variation that it takes many tanks of gas to get any meaningful data. If you want to do manual calculations, start a log. Once you get about ten tanks in the log the data will be close to the MFD figures.

    If you want more information, search for "bladder" and "guess gauge".

    Tom
     
  4. dar

    dar New Member

    Joined:
    Jun 16, 2008
    8
    0
    0
    Location:
    Washington
    Vehicle:
    2008 Prius
    I just took my 2008 in to get "fixed". On a recent road trip, I joked about getting 200 mpg ... we often hit 200 miles before one bar clicked off on the fuel gauge. I got the car back today, suposedly the fuel gauge has been recalibrated ... we will see ...

    On a side note ... my mpg ranged pretty widely ... found out the darn tank was not filling up. One time, after getting a bit more gas into the tank ... my average was 55mpg ... NOT my car ... the next fill up was 1.7 gallons and I had driven 132 miles ... I could not get another drop in the tank ... the bladder was starting to act up with 5000 miles on the car ...