28MPG Caused by Short Trips Or?

Discussion in 'Gen 2 Prius Fuel Economy' started by tetsuooooooooo, Aug 6, 2020.

  1. tetsuooooooooo

    tetsuooooooooo New Member

    Joined:
    Jul 3, 2020
    24
    5
    2
    Location:
    Virginia
    Vehicle:
    2008 Prius
    Model:
    Two
    So, I have an '08 G2 Prius with 175k miles and averaging 28MPG (calculated using not the MFD but the amount of gallons filled and miles driven). What I have already done:
    • Cleaned Throttle Body
    • Brand New Iridium Spark Plugs
    • Cleaned out the Hybrid Battery Fan
    • Cleaned MAF
    • Changed Out Inverter Fluid with Toyota OEM Fluid
    • 42F/40R PSI
    • Mobil1 High Mileage Oil
    • Lucas' Fuel Injector Cleaning
    • All Fluids Checked/Topped Off
    • All brand new brake shoes
    • I hypermile the best I can
    • Brand new air filters
    My two front tires are a few years old (have not had an alignment in years!), both at about 4" tread left. I also have never changed the transmission fluid or bled the brake fluid out and had new fluid poured in. I make lots of short trips, try to combine them but usually it's 5 to 10 miles per trip.

    Could it be the tires with low tread, no alignment done in years or short trips or all of the above? Any ideas? I have checked two apps and have no codes. I hardly run the more than a quarter of its strength, also use a sunshield purchased from here. Thank you!
     
  2. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    15,438
    8,703
    90
    Location:
    Western Washington
    Vehicle:
    2012 Prius
    Model:
    Three
    Just how short are your trips? That is clearly a factor that can produce seriously low MPG, but by no means the only thing.

    For starters, look over this questionnaire for ideas. Though it was really written for new drivers of not-so-old cars, so doesn't cover many old car issues:
    Fuel economy complaints/queries? Please copy, paste & answer these questions, esp. if you're new | PriusChat

    Do describe your typical usage pattern so we can get a clue how much that contributes. But if nothing else pops up out of this, then other ideas need to be explored. Starting with brake drag.
     
  3. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,452
    4,395
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    10 miles is enough to let the car show you good numbers if it is still capable.

    5 miles is iffy. Even a new, well-tuned Prius would struggle to show good numbers on a 5 mile total trip.

    Sometimes the hybrid battery is just too old to contribute much anymore, and you wind up burning more fuel. Looks like you covered most everything else.
     
    jerrymildred likes this.
  4. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    95,257
    43,192
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    how long have you owned the car? were the mpg's ever higher?
     
  5. tetsuooooooooo

    tetsuooooooooo New Member

    Joined:
    Jul 3, 2020
    24
    5
    2
    Location:
    Virginia
    Vehicle:
    2008 Prius
    Model:
    Two
    Typical usage: 2-4 miles a day driven. When the ICE is warmed up, the average goes up to 42-45MPG. Never heard that brake drag could be a thing. Dealership and independent mechanic and third party all tested the vehicle and found no issues with brakes.
     
  6. tetsuooooooooo

    tetsuooooooooo New Member

    Joined:
    Jul 3, 2020
    24
    5
    2
    Location:
    Virginia
    Vehicle:
    2008 Prius
    Model:
    Two
    Since 2010, but overall my MPG when ICE is warmed up goes into the mid 40s without any issues.
     
  7. tetsuooooooooo

    tetsuooooooooo New Member

    Joined:
    Jul 3, 2020
    24
    5
    2
    Location:
    Virginia
    Vehicle:
    2008 Prius
    Model:
    Two
    The HV is 65% charge on a normal day. Could be my short trips. How about never having a wheel alignment and low tread on front tires?
     
  8. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    95,257
    43,192
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    low tread improves the mpg. i wouldn't bother with an alignment unless your tires are wearing unevenly, or it isn't tracking straight.
    if you mpg's haven't gone down in 10 years, i wouldn't worry about it
     
    ukiltmybrutha likes this.
  9. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    15,438
    8,703
    90
    Location:
    Western Washington
    Vehicle:
    2012 Prius
    Model:
    Three
    If those represent multiple trips segments, such as a round trip commute where the engine cools off between segments, then your MPG will be horrid, in all gasoline cars. Traditional non-hybrids will be even worse.

    With my past cars, I very roughly guesstimated that cold engine warmup consumed as much gas as two extra driving miles, on top of the miles actually driven. I.e. a cold 2 mile segment would use 4 EPA-MPG miles worth of gas, cutting realized MPG about in half. The Prius isn't quite that bad because it doesn't get a full warmup in those short distances, but still gets awful results.

    For respectable short trip efficiency, one really needs to drive those trip in all-electric mode, either with a plug-in hybrid or a true electric car.

    Or get a bicycle, or walk, if circumstances allow. Which they do not for many people.
    That suggests that you are good.

    I've had some past cars where the calipers or pistons got sticky from corrosion, not fully retracting when brakes released, causing some drag. But between what your mechanics say, and your decent warm ICE MPG, that doesn't appear to be a problem.
     
  10. Leadfoot J. McCoalroller

    Leadfoot J. McCoalroller Senior Member

    Joined:
    May 12, 2018
    4,452
    4,395
    1
    Location:
    Pennsylvania
    Vehicle:
    2018 Prius c
    Model:
    Two
    If just driving a longer stretch gets you 42+ then the car's working fine, it just isn't well suited for your ultra-short typical trip length.

    If you want to juice the stats, you can equip the car with a block heater to pre-heat the engine before departure. This will significantly boost your numbers, if you don't mind the hassle of plugging in the heater power and managing it. You'd never recoup the savings, it would just be a stats game.
     
    Prodigyplace likes this.
  11. fotomoto

    fotomoto Senior Member

    Joined:
    Apr 22, 2009
    5,409
    3,637
    0
    Location:
    So. Texas
    Vehicle:
    Other Hybrid
    This is our typical drive scenario and we get about the same mpg's as you. I found going the plug-in route was the solution. Typically a min. 5-10 mile trip is needed to pull high mpg numbers.
     
  12. fotomoto

    fotomoto Senior Member

    Joined:
    Apr 22, 2009
    5,409
    3,637
    0
    Location:
    So. Texas
    Vehicle:
    Other Hybrid
    I'm not so sure about that. Currently (gone back) to using a gasser instead of a hybrid for regular (short) trips. Yes, the mpg's are much lower numerically but percentage wise it's a different story.

    Gasser: 20mpg (epa rated 24)=83%
    Gen 2: 28mpg (epa rated 46)=61%

    I know our Gen 4 is better with warmup mpg's but I don't have numbers.

    I spent one week purposely doubling the trip lengths in the gasser and bumped it up to 26mpg! I'd expect the same or even better with the gen 2. So, would it be possible to drive more miles to save money? :confused: Then there's the time cost factor. :coffee:
     
  13. tetsuooooooooo

    tetsuooooooooo New Member

    Joined:
    Jul 3, 2020
    24
    5
    2
    Location:
    Virginia
    Vehicle:
    2008 Prius
    Model:
    Two
    Ok that makes me feel way better! So, short trips are what's killing the average MPG. That makes total sense to me now.
     
  14. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    15,438
    8,703
    90
    Location:
    Western Washington
    Vehicle:
    2012 Prius
    Model:
    Three
    I was referring to the absolute numbers, not percentage. I.e. can you find any conventional gasser of similar vintage that meets or beats the Gen2's 28 mpg under the same conditions? I doubt it.
     
  15. DTKim

    DTKim Member

    Joined:
    Apr 11, 2012
    51
    31
    5
    Location:
    NJ
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Advanced
    If your local streets are anything like mine, you could be that inefficient with only 2-3 mile trips, especially if you let it cool down before starting it up again. If you're doing around 5 miles per leg, you should easily be in the mid-30's, but here's a few other things to consider (not already listed).

    Short trips include a lot of stop signs. It takes me a mile (slightly uphill) and 6 stop signs along the way to get to the highway. Depending on how you accelerate at each stop sign, this is a HUGE waste of fuel and can easily be down to the 20's, especially when warming up.

    HVAC use, especially the last few months in high heat can burn fuel quickly. It's possible you have everything on high for the majority of your short trips and you notice better fuel economy on longer trips because you lower the settings as things get comfortable.

    Like fotomoto mentioned, going the plug-in route does help MPGs, but you'll have the same energy efficiency issues related to stop sign acceleration and HVAC use. In fact, if you live in a high electricity rate state like mine (.185/kwh), you're still better off running on gas for anything more than a mile. If you're lucky and have low rates (supply AND delivery combined), go plug-in for your lifestyle.
     
    tetsuooooooooo likes this.
Loading...