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

Why my mpg does not match promised values?

Discussion in 'Gen 4 Prius Fuel Economy' started by Go-Green-Pal, Apr 28, 2018.

  1. alanclarkeau

    alanclarkeau Senior Member

    Joined:
    Feb 24, 2016
    7,041
    7,580
    0
    Location:
    near Brisbane, Australia
    Vehicle:
    2016 Prius
    Model:
    N/A
    I meant to say in my response that the brochure states:
    upload_2018-4-30_9-35-6.png
    FORD says:
    upload_2018-4-30_9-35-46.png ... upload_2018-4-30_9-36-31.png

    The idea of the advertised rate is to have a comparison as all vehicles are tested to the same standard. Very few people get the advertised figure, no matter what the car - in fact, there is often a different advertised figure in some countries as there are different testing procedures (here it is ADR - for Australian Design Rules). The theory is that it shows that a PRIUS uses less than ½ the fuel of an equivalent (ie Corolla/Focus) sized petrol car. You might use 15% more than the advertised PRIUS figure - and you would probably also use in the order of 15% more than a Corolla/Focus. But with a driver who uses 50% more on a PRIUS would likely also use 50%+/- more with a Corolla/Focus. Same if it was a

    As mentioned above, FUELLY shows that 2016 drivers have averaged between 3l/100k (excellent+), and 6.5l/100 (not real good) - different drivers, different climates, different geography, different driving environments. Me - I'm happy to be on the better side of average.
    upload_2018-4-30_9-40-50.png

    One thing I noted (but never told her), driving the same car in similar circumstances, my wife used a little more fuel than I did - she wasn't a hard driver, just less aware of the mechanics of the car and what would encourage it to use less.
     

    Attached Files:

    Mendel Leisk likes this.
  2. CooCooCaChoo

    CooCooCaChoo Active Member

    Joined:
    Jan 7, 2015
    886
    493
    0
    Location:
    Cow-lee-fornia
    Vehicle:
    2023 Prius
    Model:
    LE
    Tons and tons of variables in play to come to a conclusive answer, but one answer will always be the same: the driver.

    If you drive fast, you will get low mpgs. If you drive slow. you will get high mpgs.

    I get about 65mpg going to work and 80-85 coming home.
     
    alanclarkeau likes this.
  3. alanclarkeau

    alanclarkeau Senior Member

    Joined:
    Feb 24, 2016
    7,041
    7,580
    0
    Location:
    near Brisbane, Australia
    Vehicle:
    2016 Prius
    Model:
    N/A
    Yes - I can imagine it - in my last job before I retired,I was always stressed and wound up on my way to work, more relaxed "phew - survived another day" on my way home.
     
  4. Mendel Leisk

    Mendel Leisk Senior Member

    Joined:
    Oct 17, 2010
    54,473
    38,103
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    Besides speeds, strategy helps a lot. The more you can avoid unnecessary acceleration, the better. Look ahead, anticipate slow downs, keep a good space in front: you can coast through it during slowdowns, instead of braking.

    Learn too, how to lift off the gas to slip the car into electric-only, then, keep the Hybrid Synergy Indicator bar to the left of median, and the engine will stay off. Use this sparingly, it will eat up the charge faster.

    Last but not least: obey speed limits.
     
    alanclarkeau likes this.
  5. alanclarkeau

    alanclarkeau Senior Member

    Joined:
    Feb 24, 2016
    7,041
    7,580
    0
    Location:
    near Brisbane, Australia
    Vehicle:
    2016 Prius
    Model:
    N/A
    Also, the Energy Monitor gives a better idea of what's happening - the Hybrid System Indicator sometimes takes a while to catch up with what's going on (particularly the "EV" light is very approximate) - you can have the Energy Monitor on your Dash, as most of the Hybrid System Indicator is in the HUD:
    upload_2018-4-30_12-11-12.png

    And the scores are a bit deceptive - sometimes are OK, but in these 3, the lowest fuel use (2.8l/100) got the worst score:
    upload_2018-4-30_12-13-54.png
     
  6. Go-Green-Pal

    Go-Green-Pal Member

    Joined:
    Mar 26, 2018
    73
    43
    0
    Location:
    Greenville, NC
    Vehicle:
    2018 Prius
    Model:
    Three
    I did not venture into this forum before I bought the Prius and so I obviously did not read your post before. I may actually be falling under the category of folks for whom Prius is not a very good choice. I only put in about 6000 to 8000 miles per year and so it will take a long time for me to recuperate the extra expense. Also, as most of my trips are short, I am not going to get high mpg either.

    As someone else pointed out a prime plug in might be a better choice for me. However, I am not comfortable with it as we don't have facilities for charging in my small town. I would have to use just ordinary household power outlet. Further it is not clear whether it will ultimately be cheap when you factor in the electricity bill.
     
  7. alanclarkeau

    alanclarkeau Senior Member

    Joined:
    Feb 24, 2016
    7,041
    7,580
    0
    Location:
    near Brisbane, Australia
    Vehicle:
    2016 Prius
    Model:
    N/A
    What was your last car?

    I'm not a high mileage driver any more, but it's going to save me in a few years. The 48.27 MPG is still pretty good, and it will improve with rising temperatures. And PRIUS traditionally has been very low maintenance - instead of getting 40,000miles from pads and discs, you'll likely have the same brakes when you sell your car. Plus, it's a nice car to drive
     
    krmcg likes this.
  8. JimboPalmer

    JimboPalmer Tsar of all the Rushers

    Joined:
    Apr 14, 2009
    12,470
    6,862
    2
    Location:
    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    I no longer give that advice, so much of it is Gen 2 specific. I wish you all the best with your discoveries. my brother who just bought a Prime is happy on 110 volt current, so it can be done.

    Look on the bright side, 5 months of better and better MPG due to weather.
     
  9. Zythryn

    Zythryn Senior Member

    Joined:
    Apr 28, 2008
    6,154
    4,146
    1
    Location:
    Minnesota
    Vehicle:
    Other Electric Vehicle
    Model:
    N/A
    The Prius isn't a bad choice. While short trips lead to a lower MPG than the rated, the same is true for any other car out there.
    If you were looking to use less resources and be "greener" then the Prius was a good choice.
    If you are looking for the lowest fueling cost, I Prime probably would be better depending upon the cost of your electricity. How Green it would be depends upon the source of your electricity, but for most electricity is the winner.

    I know others have mentioned this, but I just have to add that referring to the EPA numbers as "promised" is really the wrong way to look at it. They give a guideline for comparison, not a promise that every individual will get that rating no matter how they drive.
     
    breakfast and jerrymildred like this.
  10. jerrymildred

    jerrymildred Senior Member

    Joined:
    Oct 28, 2016
    11,490
    14,095
    0
    Location:
    Tampa, FL
    Vehicle:
    2017 Prius
    Model:
    Two
    You'll get a whole lot higher mileage with the Prius than any other car I can think of right now. And, as @Zythryn pointed out, EPA numbers are not promises. They are just a standard comparison showing what all cars get under their particular testing methods.

    So? Unless the charging stations are free, your household electricity will be way cheaper anyway. No way would I pay the rates charged by the commercial chargers.

    If you look at your electric bill, it will be perfectly clear. Under my driving conditions, I get about 11 miles per charge in the PiP. It costs me about 39 cents to do a full charge at home. That's about 3.5 cents per mile. I just paid 2.599/gallon for gas and get about 52 mpg on average in HV mode. So it's 5 cents a mile on gas.

    In your case, with the short trips preventing optimal gas efficiency, it should be way cheaper to drive on electric than gas unless Greenville has crazy electric prices like Boston and some other places. In fact, it sounds like you're driving at much lowers speeds than I am, so you'd get even better miles per kWh.

    But that's all water under the bridge now. I would just enjoy getting better fuel economy than anyone else driving the same commute that you have. And when you take the car on a road trip, you can really have something to brag about. ;)
     
    #30 jerrymildred, Apr 30, 2018
    Last edited: Apr 30, 2018
    Zythryn likes this.
  11. Go-Green-Pal

    Go-Green-Pal Member

    Joined:
    Mar 26, 2018
    73
    43
    0
    Location:
    Greenville, NC
    Vehicle:
    2018 Prius
    Model:
    Three
    Oh no, I don't regret buying Prius. While fuel economy is good, that was not the only reason for the choice. I like the high reliability of Toyota, the abundant safety features it has and also like the hatchback style (not to mention the eco-friendly stuff).

    Even if my mpg stays at 48, it is still a bargain. My previous car was a Honda Accord and it gave me about 20 mpg in the city and 30 in highways approximately.

    Finally, I am getting 55 and 60 mpg sometimes even on short drives of 5 miles, but not always.

    I have a positive feeling that my mpg will go up once I understand Prius better.
     
  12. alanclarkeau

    alanclarkeau Senior Member

    Joined:
    Feb 24, 2016
    7,041
    7,580
    0
    Location:
    near Brisbane, Australia
    Vehicle:
    2016 Prius
    Model:
    N/A
    Also - if you do any longer trips, you'll really see an improvement.
     
  13. ssdesigner

    ssdesigner Active Member

    Joined:
    Jul 14, 2016
    304
    241
    0
    Location:
    california
    Vehicle:
    2013 Aqua
    Model:
    Persona
    I drive 3.2 miles one way to work every day, speeds topping out at 35mph. My 2 year average over 8500 miles driven is 50.4 MPG.

    In the MN winter it's around 35 MPG and without AC in warmer temps it's closer to 70 MPG. The other day I hit a 3 mile trip with 96.8 MPG.
     
    jerrymildred likes this.
  14. The Electric Me

    The Electric Me Go Speed Go!

    Joined:
    May 22, 2009
    9,083
    5,795
    0
    Location:
    Undisclosed Location
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Hmm...
    I'm going to say, you're not getting the "promised value" because Toyota advertises the EPA estimate, not a promised value. Somewhere in the fine print you'll see the words, 'Your Mileage May Vary".

    If it's a brand new Prius, I'd say you are doing pretty good. I think as tires break in, and engines break in, mileage can improve. You could check all the normal things, most notably tire PSI. But -4 vs EPA isn't really too bad.

    I found with my Prius there definitely was seasonal differences. MPG's dropped in winter, as with any vehicle. Improved in Spring, Summer and Fall.
    And if I monitored from day to day, week to week, I could be overly happy or make myself depressed. What I did was look at overall MPG for months or combined months.
    Individual drives, or individual tanks could be either optimistically misleading or devilishly disappointing but overall MPG in relationship to months of usage, or seasonal usage was what I would look at.

    I generally found in day to day urban driving, lots of city, my MPG would be less than EPA.
    BUT...
    This was off-set by being able to exceed the EPA on long road trips. I was amazed sometimes at the gas mileage I could get on a long highway drive.
    The Prius remains the best long road trip vehicle I have ever owned. ---I miss that.

    Anyway, I wouldn't worry about being 4 MPG below EPA. Give it some time.
     
    breakfast likes this.
  15. JDenyer232

    JDenyer232 Member

    Joined:
    Sep 10, 2016
    44
    46
    0
    Location:
    Maine
    Vehicle:
    2016 Prius
    Model:
    Two
    It's a new car, the engine needs to break in some. Newer engines today have very tight tolerances and it's not unusual for breaking in to affect mileage. When I first got mine I was getting upper 40's in august. Now I get mid 50's in the winter and mid 60's in the summer. Hand calculated and same route to work as I always take. Mileage improved after about 5000 miles. My commute is 35 miles each way 90% highway, some mild hills doing 70mph.
     
    Go-Green-Pal likes this.
  16. RoadNoise

    RoadNoise Active Member

    Joined:
    Jun 8, 2016
    136
    187
    0
    Location:
    Huntsville, AL
    Vehicle:
    2016 Prius
    Model:
    Two Eco
    Great ways to squeeze better mileage, Mendel. Simply drive your Prius as though you were riding a bike. On a bike, one one avoids wasting energy with excessive acceleration or braking.

    As for short trips, my circumstances allow for excellent mileage (warmer weather doesn't hurt). Take my rather frequent short trips to the grocery store. Here is a typical snapshot from home to store. 71 F, cold start, no wind or rain.
    shortdrive1.jpg


    The trip home is a very different story. Shopped for about about 30 minutes while parked in a garage, so the engine had time to cool down..
    shortdrive2.jpg

    Leg home not the best...but an average of 87.4 MPG round trip.

    The difference? 171 ft of altitude change.
     
    Tideland Prius and jerrymildred like this.
  17. RCO

    RCO Senior Member

    Joined:
    Aug 31, 2016
    3,709
    5,182
    0
    Location:
    Cornwall
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I would suggest you try to forget about chasing the hypothetical numbers and just enjoy the fantastic car. Honestly, a daily average mpg is not really representative. Even a tankful of gas is only slightly more realistic. If you're really, really interested in your average fuel, keep a note of your average at every fill-up and average it over the whole year. You could use Fuelly App or a spreadsheet to help, but just pencil and paper would suffice. The advice from everyone else is sure to help, but a gentle right foot and smooth driving style is the secret. Over time you'll learn new things by trial and error - just try not to overthink it! Your doing great even if you use a bit more than other Prius drivers, is still far less than you would in a more conventional car.
     
  18. Go-Green-Pal

    Go-Green-Pal Member

    Joined:
    Mar 26, 2018
    73
    43
    0
    Location:
    Greenville, NC
    Vehicle:
    2018 Prius
    Model:
    Three
    I signed up for fuelly and am maintaining it carefully. Ya, you are right; one should not be overly concerned about the numbers. The funny thing is I am already happy with the 48 I am getting considering I was only getting about 22 or so in similar situation before in my 2002 Honda Accord. But, I was trying to keep up with the Joneses. :p:sick:

    But, I am confident that my mpg will improve over time. In fact, it has already increased a bit and gone to 48.7 or so (over the car's entire life).
     
  19. alanclarkeau

    alanclarkeau Senior Member

    Joined:
    Feb 24, 2016
    7,041
    7,580
    0
    Location:
    near Brisbane, Australia
    Vehicle:
    2016 Prius
    Model:
    N/A
    You can link your Fuelly page to your PriusChat page.
     
  20. axle2152

    axle2152 Active Member

    Joined:
    May 14, 2013
    266
    209
    0
    Location:
    Atlanta, GA
    Vehicle:
    2018 Prius Prime
    Model:
    Prime Plus
    There's too many reasons why fuel economy is really bad or really good on the prius... 50,000 miles and averaging something like 55.6 MPG, lot of highway miles for me. I also cheat and have a OBD2 adapter and often look at a lot of the things they don't tell you...also watch battery temps too. Yes, that too will effect gas mileage. The ideal range seems to be between 85-115 F (roughly), if it is above or below that the output power will be less than 21 kW.

    However, what I can say is this, the two biggest things is the outside temp and the driver. If it is really cold, really hot, fuel economy will take a hit. If you accelerate quickly or brake hard, another hit. If your commute is short and the car can't warm up completely probably will take a hit. Those are all things that a bigger factors, more so than tire pressure -- sure if adds up, but I think we can agree that if the car has been sitting in the hot sun all day that will have a bigger impact on fuel economy than having your tires at 35 PSI than 40 PSI.