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

Good MPG bad Mileage when Fueled

Discussion in 'Gen 2 Prius Fuel Economy' started by Jake West, May 25, 2022.

  1. Jake West

    Jake West New Member

    Joined:
    Apr 21, 2022
    2
    1
    0
    Location:
    UK
    Vehicle:
    2007 Prius
    Model:
    Five
    So, I'm getting very good mpg currently (56) and I'm doing alot of coasting, driving between 60 - 70mph and then some town driving too on full ev mode. But it seems like I'm not getting that many miles out of my 2008 prius before the guage shows low again.... at the moment, I've gone a total of 310 miles before fueling again - is this normal?


    I'll put some more details here:


    - What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations) = 53 - 56MPG

    - What fuel economy are you expecting and WHY? = Not expecting anything more than what I'm getting now, more intrigued as to why I'm not getting more miles.

    - What are the approximate outside air temps? = Between 11°c - 20°c

    - How long are your trips? = No more than an hour at a time

    - How much of it is city vs. highway? = Combination of both, some days is highway some days are city

    - Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving? = Average speed is 33mph... but if I did a commute to one of my work places, it would be 68mph

    - What region/state are you in? (if you haven't set your location in your profile) = UK

    - What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc.) = Few gradual hills, nothing steep, quite flat for most part

    - Is your oil overfilled? (i.e. above the full mark on the dipstick) = Nope

    How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here) = Not sure... need to look into this

    Have you had your alignment checked? Any pulling or abnormal tire wear? = Nope

    - Are you using the factory tires and wheels? If not, please indicate tire make, model and size (e.g. Goodyear Assurance Fuel Max 185/65R15). = Factory tires, replaced a few months ago

    - What are your tire pressures? = 35 on front 32 on back

    - Make, model, year, engine and transmission of previous car? (e.g. 08 Honda Civic Si 2.0L 4 cylinder, manual transmission) What did you actually get on the same trips/commute? (Please give us actual numbers, not EPA ratings.) = 2008 Toyota Prius T-spirit 1.5

    - How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking? = Trying to stay in electric only mode by feathering the throttle as much as possible

    - Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on? = Not normally, no

    - Are you driving using D or B mode? = D

    - HVAC settings? Are you using the heater, AC, auto mode, etc.? If using auto, what temp is it set to? = Normally set to auto with a temp of 20.5°c

    - If reporting a mileage drop, did anything significant change on your car (e.g. accident, hit a curb or big pothole throwing off alignment, oil change/other maintenance/repairs, changed tires or wheels, etc.) or your commute? = Nothing major has impacted this and nothing significant has happened
     
  2. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    107,571
    48,862
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    how are you figuring fuel economy, dividing miles by gallons pumped?

    how many gallons does it take when you fill up from the flashing bar?

    something may need calibrating, unless you're putting in ten gallons. could be a pollution control issue too.
    have you tried different pumps and gas stations?
     
    Mendel Leisk likes this.
  3. Jake West

    Jake West New Member

    Joined:
    Apr 21, 2022
    2
    1
    0
    Location:
    UK
    Vehicle:
    2007 Prius
    Model:
    Five
    = That's my next try - different gas station



    So I'm assuming the prius can go more that 310 miles!
     
    bisco likes this.
  4. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    6,058
    5,783
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    Tons of details except for perhaps the second most important...
    So we know you're refueling at ~310 miles on a tank (is this consistent?)

    How much gas is going in the tank when you fill it?
     
    fuzzy1 and Mendel Leisk like this.
  5. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    6,058
    5,783
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    Also, don't forget one very obvious potential problem.
    Let's assume you get 50 mpg on your display.
    your MFD shows 50mpg and 310 miles when the gas gauge starts blinking.
    You stop at gas station and fill up, adding 9 gallons of fuel.
    Weird, should have only needed a bit over 6 gallons......
    why would the fuel tank be 9 gallons low if I only burned 6 gallons with the engine?
    Potentially? Fuel leak somewhere.....3 gallons had to go somewhere...maybe on the ground or in the air.
     
  6. mmmodem

    mmmodem Senior Taste Tester

    Joined:
    Nov 17, 2011
    2,732
    1,703
    0
    Location:
    Bay Area, CA
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    A lot of good details. Just missing one more. How many gallons of fuel to go that 310 miles? And specify imperial or US gallons.
     
    fuzzy1 and Mendel Leisk like this.
  7. dolj

    dolj Senior Member

    Joined:
    May 14, 2012
    7,448
    3,751
    0
    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    The OP said in post #3 he thought maybe 24 litres, so 6.3 US gal which is a couple of litres more than half a tank.
     
  8. Another

    Another Senior Member

    Joined:
    Jun 22, 2021
    1,802
    508
    0
    Location:
    Naples, Florida
    Vehicle:
    2007 Prius
    Model:
    Touring
    Do you ever turn off the A/C when in AUTO mode? At 20.5°C unless it’s very warm outside, you should be able to stay comfortable without the compressor running and the temp control can still operate. Takes a load off the battery. Just select the CLIMATE button and disengage the A/C.
     
  9. dolj

    dolj Senior Member

    Joined:
    May 14, 2012
    7,448
    3,751
    0
    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    I don't know why people fuss with the A/C so much. If you run it in Auto and the compressor is not required for cooling, it doesn't run it.
     
  10. Another

    Another Senior Member

    Joined:
    Jun 22, 2021
    1,802
    508
    0
    Location:
    Naples, Florida
    Vehicle:
    2007 Prius
    Model:
    Touring
    Where’s his set point?
     
  11. jdenenberg

    jdenenberg EE Professor

    Joined:
    Nov 21, 2005
    3,831
    1,825
    1
    Location:
    Trumbull, CT
    Vehicle:
    2020 Prius
    Model:
    LE AWD-e
    I always shut off the AC compressor about 5 minutes before stopping at the destination to dry off the coils a bit and avoid building up mold.

    JeffD
     
  12. TMR-JWAP

    TMR-JWAP Senior Member

    Joined:
    Aug 12, 2016
    6,058
    5,783
    0
    Location:
    Columbia, SC
    Vehicle:
    2007 Prius
    Model:
    Touring
    Just to minimize how dumb we look, a new members posts don't show up until they've been verified by a moderator. SO when a question is asked, sometimes the answer may have already been provided, but it's just not showing up yet. The moderated post eventually shows up in chronological order, so it ends up looking like a question was asked about information that was already provided. In reality, the moderated post didn't show up until after the question was asked.
     
  13. dolj

    dolj Senior Member

    Joined:
    May 14, 2012
    7,448
    3,751
    0
    Location:
    Wellington, New Zealand
    Vehicle:
    2007 Prius
    Model:
    N/A
    When the OAT is between 11°C - 20°C then it will be heating and the compressor won't be doing much.
    I try to do that too (if I remember), but that is different from fussing with the Auto button.
    Sorry about that, yeah, that's happened to me too.
     
    #13 dolj, May 28, 2022
    Last edited: May 28, 2022