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Calculated MPG vs. Indicated MPG of the c - Please post your results

Discussion in 'Prius c Fuel Economy' started by F8L, Mar 11, 2012.

  1. tomheik

    tomheik New Member

    Joined:
    Mar 18, 2012
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    Location:
    Fort Lauderdale
    Vehicle:
    2012 Prius c
    Model:
    Two
    I filled up for the second time today at 1,267 miles. This was 5 miles after the low fuel warning light came on. This time I filled to the top. Here are my cumulative fuel consumption stats:

    I have driven 1,164 miles since I topped the tank after I got it from the dealer- 103 miles. I have put in 6.158 and 8.825 gallons for a total of 14.983 gallons. I calculate my cumulative MPG at 77.68 which is pretty good for mainly city driving.

    I pay attention to the displayed MPG on individual trips and I have hit 80 plus on several occasions. I have been driving in ECO mode exclusively and glide a lot. Plus we have warm weather down here in South Florida which helps.
     
  2. vinnie97

    vinnie97 Whatever Works

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    ^78 mpg cumulative is earth-shattering (well beyond "pretty good," IMO ;)). Can't believe no one has responded to your results yet.

    Finally filled it up for the second time today, and here are my comparatively disappointing results:

    Date: 4-26
    Miles driven: 558
    Gallons Pumped: 9.168 (single top-off)
    Hand-Calculated MPG: 60.9
    Displayed MPG: 64.4
    Tire Size / Wheel size: standard
    Tire Brand / Model: stock
    Tire PSI (Front / Back): 42/40
    Seasonal Conditions: A/C used on a few days when temp rose well above 90.
    Commute Length: n/a
    Hypermiling Techniques: regenerative braking mainly
    Other: More than a handful of trips under 5 miles means there is a lot of room for improvement. I only went on the interstate once. Most driving was done in city conditions and a state highway (30-50 mph). Additionally, I am a sucker for using cruise control and tend to drive right around the speed limit or under in the right/slow lane when traffic is light. Finally, I was not in ECO mode for the majority of this tank, if not for the totality. As expected, when driving with the same technique, the mode chosen seems to ultimately make little difference in fuel consumption, though it might have a bigger impact with excess A/C usage.

    It seems the single topoff method is not providing me with accurate results on the display. I might try 2 topoffs on the next fillup, but I don't want to risk damage to the bladder.
     
  3. kkim

    kkim Active Member

    Joined:
    Jan 27, 2007
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    Location:
    kauai, hawaii
    Vehicle:
    2012 Prius c
    Model:
    Three
    Prius c does not have a bladder tank.
     
  4. vinnie97

    vinnie97 Whatever Works

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    Mar 20, 2010
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    Vehicle:
    2018 Tesla Model 3
    Model:
    N/A
    Whatever it has then. :p I'm pretty sure it's a charcoal filter, which could be subject to damage from the same mechanism (overfilling).
     
  5. luthyone

    luthyone New Member

    Joined:
    Mar 24, 2012
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    Location:
    fairfield, ca
    Vehicle:
    2012 Prius c
    Model:
    Two
    3rd fill up and my average was 43.4 mpg . The computer read 45.2 mpg Again, this is with 3 occupants, the driver(me) weighing in at 300lbs, a/c running, windy everyday. Trips are 10% highway and 90% city. City route is routinely 7.5 miles round trip.
     
  6. kindlewood

    kindlewood New Member

    Joined:
    Apr 12, 2012
    39
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    Location:
    Cape Cod, MA
    Vehicle:
    2012 Prius c
    Model:
    Two
    Year of vehicle: 2012 Prius C
    Date: 4/26/12
    Miles driven: 510.2
    Gallons Pumped: 8.987
    Hand-Calculated MPG: 56.77
    Displayed MPG: 59.2
    Average Speed: 39mph (I think)
    Tire Size / Wheel size: 15"
    Tire Brand / Model: Standard for Prius C
    Tire PSI (Front / Back): Not sure, haven't checked since I received the car.
    Seasonal Conditions: (please include A/C usage and temp setting if applicable): Spring weather, with morning temps averaging between low to mid-40s, to low 50s. Daytime temps getting into the high 50s, to mid 60s. I used the A/C on occasion (maybe 15-20%), but tried cracking the windows when traveling slower than 40mph. Also turned off the A/C after it was cool enough in the car.
    Commute Length: Roughly 60 miles, round trip. I average about 70 miles in the car most days. While I drove on the highway 3, or 4 times, for maybe a total of 50 to 60miles, I switched out to mostly back roads about halfway through my first week of commuting.
    Hypermiling Techniques: Eco Mode 99% of the time. I switched between the Eco Score and the Energy Use screen throughout. I attempted, with some success, to use the pulse and glide method, but mostly relied on regenerative braking. Because the car is so light, I'm finding it difficult to maintain a nice long glide. This is something I've been able to take more advantage of in my father's 2009 Prius hatchback.
    Other: (this could explain why a tank was bad or good or other unusual conditions like a rain storm, new tires, lots of short trips, etc.): Nothing else I can think of off the top of my head. I don't think I will do as well with my second tank, since I was forced to travel nearly 150 miles so far on the highway. Also, since I had my whole family with me, I used the AC almost the whole trip. I've gotten better mpg on the back roads than my first tank, but the highway average of about 54.5mpg (displayed), will probably bring my actual calculated mpg down a bit.
     
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  7. vinnie97

    vinnie97 Whatever Works

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    ^That last bit is the easiest part, just a copy/paste. :)
     
  8. GraeSack

    GraeSack New Member

    Joined:
    Apr 4, 2012
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    Location:
    Lacey, WA
    Vehicle:
    2012 Prius c
    Model:
    Three
    Just got my Pc3 on Saturday. Have a forty mile trip I use for test. It's a mix of urban/suburban and freeway. Saturday averaged 56.1 mpg per display. Sunday, I set the tires to 40/38 and put in a lower grille block. Same trip, same time and weather, averaged 60.2. When I get down to half a tank, I'll fill up and check figures--maybe next weekend.

    All the best.
     
  9. kindlewood

    kindlewood New Member

    Joined:
    Apr 12, 2012
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    Location:
    Cape Cod, MA
    Vehicle:
    2012 Prius c
    Model:
    Two
    I actually figured it was super easy, but just never bothered to look into it...I'm lazy that way. :p

    As you can see, I've fixed my laziness and actually added fuelly.com to my signature. Thanks for motivating me. :)
     
  10. managerman

    managerman Prius v Nerd

    Joined:
    Mar 12, 2012
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    Location:
    Columbus, OH
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Third tank down..best one so far...

    Year of vehicle:2012
    Date:5/2/12
    Miles driven: 512.9
    Gallons Pumped: 8.83
    Hand-Calculated MPG: 58.1
    Displayed MPG: 59.2
    Average Speed: 25
    Tire Size / Wheel size: 15"
    Tire Brand / Model: Turanza EL400 02
    Tire PSI (Front / Back): 43/40
    Seasonal Conditions: little AC use...nice temps in Columbus, OH
    Commute Length: 5 miles each way to work....some other longer trips also..
    Hypermiling Techniques: Pulse and Glide
    Other: None
     
  11. maverickf

    maverickf New Member

    Joined:
    Nov 17, 2011
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    Location:
    Southern California
    Vehicle:
    2012 Prius c
    Model:
    Three
    Year of vehicle:2012
    Date:5/3/12
    Miles driven: 455
    Gallons Pumped: 8.08
    Hand-Calculated MPG: 56.3
    Displayed MPG: 61.0
    Average Speed: -
    Tire Size / Wheel size: 15"
    Tire Brand / Model: Factory
    Tire PSI (Front / Back): 40/38
    Seasonal Conditions: ~60-70F
    Commute Length: 74 miles (round trip), 94% Hwy.
    Hypermiling Techniques: Pulse and Glide
    Other: None
     
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  12. kindlewood

    kindlewood New Member

    Joined:
    Apr 12, 2012
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    Location:
    Cape Cod, MA
    Vehicle:
    2012 Prius c
    Model:
    Two
    Quick update.

    My second fuel up.

    Date: 4/2/12
    Miles driven: 506.6
    Gallons Pumped: 8.687
    Calculated MPG: 58.317
    Displayed MPG: 60.0
    Average Speed: - (reset the trip info. before checking...)
    Tire Stuff: Same as before (still haven't checked my tire pressure)
    Seasonal Conditions: mid-40s to high-50s. A few days of rain. Minimal AC (Maybe 100 miles of it with AC on, mostly because my whole family was with me).
    Hypermiling Techniques: Pulse and Glide. Regenerative Braking.
    Other: That's all I can think of this time.
     
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  13. kkim

    kkim Active Member

    Joined:
    Jan 27, 2007
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    Location:
    kauai, hawaii
    Vehicle:
    2012 Prius c
    Model:
    Three

    3rd fill up

    Year of vehicle:2012
    Date:02may12
    Miles driven:444.3
    Gallons Pumped:8.252
    Hand-Calculated MPG:53.84
    Displayed MPG:55.8

    Average Speed:
    Tire Size / Wheel size:175/65, 6.5x15 alloy
    Tire Brand / Model: Turanza EL400 02
    Tire PSI (Front / Back): 36/33
    Seasonal Conditions: (please include A/C usage and temp setting if applicable) a/c on maybe 50%, set to 73*
    Commute Length: 13 miles one way
    Hypermiling Techniques: paying attention to HSI gauge, car set to "normal" mode vs ECO
     
    1 person likes this.
  14. kenp11

    kenp11 Junior Member

    Joined:
    Apr 2, 2012
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    Location:
    Orange
    Vehicle:
    2014 Prius Plug-in
    Model:
    Plug-in Base
    I posted in a differnt place. My receits say i am getting 45MPGavg but my guage says 47 hiway 51 city
     
  15. jamesguy13

    jamesguy13 YoungPrius

    Joined:
    Apr 28, 2012
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    Location:
    Nanaimo, B.C. Canada
    Vehicle:
    2012 Prius c
    Model:
    N/A
    Year of vehicle:2012
    Date:9/5/12
    Kilometres driven: 842 or 523 miles
    Litres Pumped: 31.994 or 7 gallons
    Hand-Calculated L/100km: 3.79 or 62mpg
    Displayed L/100km: 3.8 or 61.9mpg
    Average Speed: -
    Tire Size / Wheel size: 15"
    Tire Brand / Model: Factory
    Tire PSI (Front / Back): unknown (Dealership levels)
    Seasonal Conditions: ~60-70F, 10-18 degrees Celsius
    Commute Length: 44 km (round trip), 94% Hwy.
    Hypermiling Techniques: Gliding, Careful driving, Conserving momentum, Hill techniques
    Other: Drove 250km highway, the rest city
     
    1 person likes this.
  16. pakitt

    pakitt Senior Member

    Joined:
    Aug 10, 2009
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    Location:
    Colorado
    Vehicle:
    2021 Prius Prime
    Model:
    Limited
    From what I am reading so far it seems that the MFD of the Prius C is about 2MPG off, or when the MPG is around 45-55, 4-6% - that is very similar to the Prius 2010, and from what I am reading, also of the Prius 2012. There some exceptions where it is actually "spot on" or sometimes where I read the error is well beyond 6% on a single tank. But on average I would say that 5%-6% is error average - don't you think?

    It makes sense that if Toyota has sw/hw that works consistently well, with 5% that most public does not care about, they would not change it between models.

    At least we know that it is constant - it didn't get better towards 0%, but not even got any worse.

    Thanks to everybody reporting their stats!
     
  17. alfon

    alfon Senior Member

    Joined:
    May 17, 2009
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    Location:
    seaside, oregon
    Vehicle:
    2010 Prius
    Model:
    III
    I can confirm after over 71,000 miles the computer
    generated mpg over reads 2.5-4 mpg.

    In summer it appears the computer is less off; in the
    winter it appears to over read more.

    My last fill up was only 1 mpg off (warmer weather). Now for the last 2,000 miles it has been off 3 mpg over read. I just
    compensate for it, but I would like to have it read at least
    99% accurate....
     
  18. DC ebikes

    DC ebikes New Member

    Joined:
    Apr 28, 2012
    24
    8
    0
    Location:
    Pittsburgh
    Vehicle:
    2012 Prius c
    Model:
    Two
    Year of vehicle:2012
    Date: May 8, 2012
    Kilometres driven: 516 miles
    Litres Pumped: 8.78 gallons
    Hand-Calculated L/100km: 58.77 mpg
    Displayed L/100km: 59.8 mpg
    Average Speed: -
    Tire Size / Wheel size: 15"
    Tire Brand / Model: Goodyear Assurance
    Tire PSI (Front / Back): unknown (Dealership levels)
    Seasonal Conditions: ~60-70F, some Sun, some Rain
    Commute Length: 74 miles (round trip), two lane
    Hypermiling Techniques: Gliding, Careful driving, Conserving momentum, Hill techniques
    Other:
     
    1 person likes this.
  19. managerman

    managerman Prius v Nerd

    Joined:
    Mar 12, 2012
    228
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    Location:
    Columbus, OH
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
    Fourth tank down..They just keep getting better and better. I have attached some summary stat pics of this tank and the stats since I have owned the car...

    Year of vehicle:2012
    Date:5/13/12
    Miles driven: 550.2
    Gallons Pumped: 9.22
    Hand-Calculated MPG: 59.7
    Displayed MPG: 60.9
    Average Speed: 26
    Tire Size / Wheel size: 15"
    Tire Brand / Model: Turanza EL400 02
    Tire PSI (Front / Back): 43/40
    Seasonal Conditions: little AC use...nice temps in Columbus, OH
    Commute Length: over 50% highway on this tank
    Hypermiling Techniques: Finding that I can travel above 42 mph and with the ICE on with low RPM's and catch the sweet spot of 75-100 MPG...Works great!
    Other: None
     

    Attached Files:

  20. -CC-

    -CC- Just sipping fuel since '08

    Joined:
    Mar 9, 2008
    12
    0
    0
    Location:
    Michigan's Thumb
    Vehicle:
    2012 Prius c
    Model:
    Three
    This is my 3rd complete fuel-up. The mpg display has continued to show about 4% higher than the calculated values.

    Year of vehicle:
    2012
    Date: 5/12/12
    Miles driven: 480.4
    Gallons Pumped: 7.80
    Hand-Calculated MPG: 61.59
    Displayed MPG: 63.9
    Average Speed:
    Tire Size / Wheel size: 175/65 15
    Tire Brand / Model: Goodyear / Assurance
    Tire PSI (Front / Back): 35/33
    Seasonal Conditions: pleasant MI spring--no heat or A/C
    Commute Length: 22 miles-- 50/50 mix of 55 mph highway and city streets
    Hypermiling Techniques: P&G etc., all miles in Eco Mode

    Other: This tank included two 85 mile trips that included freeways as well as stop & go city traffic. Overall, it is easier to get mpg over the EPA numbers with the "c" than it is with the 2nd generation (2008) Prius. (At least that is my current opinion. :))