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Help with reduced gas mileage over time

Discussion in 'Gen 3 Prius Fuel Economy' started by chrisc436, Jan 14, 2013.

  1. chrisc436

    chrisc436 New Member

    Joined:
    Jan 14, 2013
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    Vehicle:
    2010 Prius
    Model:
    III
    - What fuel economy are you getting and how are you determining fuel economy? (trip computer or manual calculations) 38 mpg via trip computer

    - What fuel economy are you expecting and why? expect to be getting 45- 48 MPG

    - What are the approximate outside air temps? cool now but over all it is mild summers can be 105 but no snow in winter

    - How long are your trips? mostly short

    How old is your 12v battery? What is the voltage reading of your 12v battery after sitting over night? (Method Here) new 4-5 month old

    Have you had your alignment checked? Any pulling or abnormal tire wear? just had one

    - How much of it is city vs. highway? Roughly what's the average speed in overall and and of each segment? Is there a lot of stop and go driving? mostly city 35-40 mph, stop and go traffic

    - What's the terrain like of your drives? (e.g. flat, gentle hills, steep hills, etc) mostly flat

    - What are your tire pressures? 38- 40

    - Is your oil overfilled? (i.e. above the full mark on the dipstick) don't know

    - 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.) use to have Honda Odyssey 1997 now have Have 2009 prius mostly short trips

    - What region/state are you in? (if you haven't set your location) sacramento CA

    - How are you trying to drive (e.g. trying to stay in electric only?) and how hard are you braking? usually try to stay in EV mode

    - What modes are you using, if any? "normal", EV, power, eco?

    - Are you "warming up" the ICE (internal combustion engine) by letting it idle after powering on? yse

    - 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? usually have those on if needed

    - 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). 165/65R 15

    - 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? no significant changes.

    I am writing to ask if most prius's start to get reduced mpg over time. I have 80,000 miles on the car and drive mostly city in stop and go traffic. We take care of the car in terms of getting oil changes, tires alignments. Our car is getting about a 20% reduction in mpg since we bought the car. (Went from getting 48 mpg now getting 38 mpg) this seems significant to us. Any help would be appreciated
     
    #1 chrisc436, Jan 14, 2013
  2. F8L

    F8L Protecting Habitat & AG Lands

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    Chris, give us a bit more background.

    How long have you had the car?

    How long have you driven it on this particular commute and what was the mpg before it went down?

    What exact tires do you have and where they on the car when you were getting good fuel economy?

    What is the 12v battery voltage? New doesn't always mean good.

    How long is your commute?
     
    #2 F8L, Jan 14, 2013
  3. TNGator

    TNGator Junior Member

    Joined:
    Nov 24, 2012
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    Vehicle:
    2012 Prius
    Model:
    Two
    Try running tire pressures at 44 front, 42 rear, eco mode only, and do some homework on hypermiling (plenty of threads on pc and clean mpg) There are so many factors that effect mpg's. I'm no expert, but I have had better mpg's doing these things. I'm sure some of the senior members will have more knowledge to share. Good luck!
     
    #3 TNGator, Jan 14, 2013
  4. walter Lee

    walter Lee Hypermiling Padawan

    Joined:
    Oct 26, 2009
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    Location:
    Maryland
    Vehicle:
    2010 Prius
    Model:
    III
    I've only driven my 2010 Toyota Prius III for about 30,000 miles over the last three years. My 2010 Toyota Prius III fuel efficiency has increased over these three years mainly because my hypermiling skills have gotten better. My only hardware upgrade has been adding a FE monitor called a ScangaugeII.

    1) Prius mpg drops as much as 20% during wintertime and rises in the summertime. For example, last summer I got as high as 71 mpg (I'm a skilled Hypermiler) - however, during the last Fuel Efficiency challenge from 2012 October-December my mileage has dropped as low as 50 mpg (30% drop in fuel efficiency) despite all my efforts.

    2) At 80,000 miles it is likely that your Prius is not using the original equipment (OE) tires - a Prius can lose up to 5 mpg if non Low Rolling Resistant (LRR) tires are used. What brand /model of tires are you using?

    3) A Prius is less energy efficient if the ICE is used to warm it up before driving. If you want to warm up your car before driving it and you have access to a electrical outlet in the morning - consider installing an engine block heater (EBH) and using that to warm up your Prius instead. Barring safety concerns, the most fuel efficient way to drive a Prius is just turn it on and drive it

    4) When driving in stop-and-go urban traffic - a 2010 Prius is more fuel efficient when set to normal/power mode - you should avoid using EV mode or Eco mode. Draining your traction battery will make the Prius burn more fuel and make it run inefficiently

    5) when the temperature drops below 60 F block the bottom grill (keep top grill uncovered)

    6) make sure the next oil change uses 0w20 synthetic oil

    7) short trips can reduces fuel efficiency on a Prius - one strategy to mitigate this effect is to schedule/plan multiple short trips in sequence ( only 15-30 minutes apart - note that a 2nd generation Prius ( 2004-2009 Prius) gets even better fuel efficiency than a 3rd gen Prius if you string short trips together becaus of its Coolant Heat Recovery System (CHS). If your trips do not add up to more than 10 miles/day and you have an electric outlet available - consider switching to a Prius Plug-in if your trips do not add up to more than 60 miles/day and you have an electric outlet available consider switching to a 2012 Nissan Leaf or a 2013 Ford Energi(plug-in version of the C-max).

    8) keep the cargo/weight that the Prius has to carry in the back to a minimum.

    9) The Prius fuel efficiency is very sensitive to road conditions - road construction, rough road surfaces, and rain/snow/ice on the road can cause the Prius MPGs to drop like a rock.
     
    #4 walter Lee, Jan 14, 2013
  5. Munpot42

    Munpot42 Senior Member

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    Location:
    Santa Monica, Ca. 90405
    Vehicle:
    Other Hybrid
    Could be something as simple as more aggressive driving habits over time, that happened to me, then reviewed some hypermilling tips on this forum and my mileage came up a bit, had to break myyself of some bad drivng habits I picked up.
     
    #5 Munpot42, Jan 14, 2013
  6. Former Member 68813

    Former Member 68813 Senior Member

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    If the MPG drop is not due to a cold season, I would do a good injector cleaner like Techrone concentrate. It helped me some with MPG this fall.
     
    #6 Former Member 68813, Jan 15, 2013
  7. szgabor

    szgabor Active Member

    Joined:
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    Location:
    Oceanside NY
    Vehicle:
    2012 Prius
    Model:
    Two
    I think the clues are:

    short trips

    new to Prius ..

    too low tire pressure

    letting the car idle while warming up !!!!!! THIS is big combined with short trips !!!

    trying to use EV ... that could be VERY counterproductive !!!!!

    just my 2c
     
    #7 szgabor, Jan 16, 2013
  8. Former Member 68813

    Former Member 68813 Senior Member

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    Location:
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    Heads up: I just noticed OP is one time only poster.
     
    #8 Former Member 68813, Jan 17, 2013
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