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Fuel consumption

Discussion in 'Gen 2 Prius Main Forum' started by Lodrun, Feb 18, 2010.

  1. Lodrun

    Lodrun My proper car is an MGC

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    I am very disappointed with the fuel consumption of my 2007 Prius T Spirit. I have never read a report from anyone getting less 45 urban miles per gallon. However, I find that the vehicle consistently returns only around 34 mpg (Imperial, not US) in town. Is this normal or is there something very wrong?
     
  2. Rokeby

    Rokeby Member

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    Lodrun,

    :welcome: to PRIUSchat. :cheer2:

    Given the scant information that you have provided, there is no way
    to tell if there is anything wrong with your car. Chances are it's OK,
    and all that is needed is an attitude adjustment on your part to get
    the FE/MPGs you've heard about.

    There are innumerable threads here on how you can increase your
    mileage with litle effort. So, I recommend that you use the search
    tool to dig into the gold mine of info at your fingertips.

    That said, here are a few ideas to consider:
    * Run your tires at 42 psi front, 40 rear
    * Short trips -- less than 10 miles or so -- are FE killers
    * Carrying extra weight saps FE
    * Stop-and-go driving reduces FE, learn to "drive without brakes"
    * Overly rapid starts reduce FE
    * Trying to run on the HV battery alone uses extra gas (?? Not
    intuitive I know, but you reading here will tell you why.)
    " Grill blocking" retains engine heat and increases FE.

    Well, there's lots more to add. You'll be better off if you read about
    all this on your own.

    Hang in there, you can do it. Good driving and high FE/MPGs to you.
     
  3. apriusfan

    apriusfan New Member

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    Also, keeping your car outside in winter-time is absolutely lethal to FE.
     
  4. Patrick Wong

    Patrick Wong DIY Enthusiast

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    That is equivalent to 28 miles / US gallon, which is quite bad.

    I also recommend that you check tire pressure, and inflate to 42/40 psi. Check wheel alignment and make sure the parking brake is not dragging on the rear wheels.

    What happens when you take a long road trip of 100 miles or more? What is your fuel consumption then?
     
  5. indyhairball

    indyhairball New Member

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    If my conversion is correct that would be about 41 mpg is US gallons. That's not bad mileage. My 2008 averages 40 to 45 mpg during cold weather and 45 - 50 mpg during warm or hot weather. All my number and most of the other numbers you are seeing are in US gallons.
     
  6. cwerdna

    cwerdna Senior Member

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    You got your conversion wrong. Imperial gallons are larger than US gallons. It ends up being about 28 miles per US gallon. See [ame=http://www.google.com/search?q=34+miles+per+imperial+gallon+in+miles+per+us+gallon&ie=utf-8&oe=utf-8&aq=t&rls=org.mozilla:en-US:eek:fficial&client=firefox-a]34 miles per imperial gallon in miles per us gallon - Google Search[/ame].
    Since this is your first post, it'd be helpful to copy and paste the questions from http://priuschat.com/forums/gen-iii...ry-copy-paste-fuel-economy-questionnaire.html and answer the best you can. Otherwise, we don't have much to go on.
     
  7. indyhairball

    indyhairball New Member

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    Thanks. Math was never my strong suit.
     
  8. Lodrun

    Lodrun My proper car is an MGC

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    Thanks for all this. I run the tyres at 38/36 psi (the Owner's Manual recommends 35/33 psi). I would like to know Toyota's view on 42/40. Nearly all my journey's are less than 10 miles and there's nothing I can do about it. The car is also parked outside and there's nothing I can do about that either. It is winter of course, and a pretty cold one too.

    Most of the FE tips I have read could apply equally to any car. I do feel disappointed that with all the hype, the urban economy is little better than my old Honda Accord when driving in a similar way.
     
  9. GrumpyCabbie

    GrumpyCabbie Senior Member

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    Yikes that's bad! I use mine as a cab and still get around 47 mpg over the winter time. 99% of my work is stuck in town with lots and lots of bumper to bumper crawling at 20 mph. This is where the Prius comes into its own. On a long motorway run I can easily get 60-65mpg.

    Check the tyre pressures. I've found the Prius is very susceptible to tyre pressures. If you are low even by a few psi on one tyre it will affect things noticeably.

    Some of our US friends run their tyres much higher than the Toyota recommendations as this gives them much better and more reliable economy but beware that doing this will affect your steering and handling - esp in the wet! Also, if plod checks them after an accident you could be in the smelly stuff upto your neck!

    So, check tyre pressures, air filter or service records, make sure the oil is the correct type and ease off with that right foot of yours a little. :D
     
  10. Lodrun

    Lodrun My proper car is an MGC

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    Last weekend I did a 300 mile round trip, mostly motorway and close to the legal speed limits. The overall consumption was 47.5 which, again, I find disappointing. I wonder if I should get the car checked?
     
  11. xsmatt81

    xsmatt81 non-AARP Member

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    TP indeed has a large factor. My avg has been stuck around 45-47mpg since i bought the car. My best was on a trip to roswell NM where i got 56mpg when i pulled into my hotel. I just DRIVE it anymore. I normally fill up around 430 on the tank, which is pretty good..i can stretch it..but don't risk it.

    leave my TP at 40/38 give or take. I used to run like 45/43..but forget it WAY to bumpy. I would rather waste 1-2 mpg..than have my teeth rattle around in my skull.
     
  12. cwerdna

    cwerdna Senior Member

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    Can you please copy and paste the questions from http://priuschat.com/forums/gen-iii...ry-copy-paste-fuel-economy-questionnaire.html and answer the best you can? You've answered some items already but there are some details that'd help. What are the "legal speed limits" there? I've never been to Europe so I have no clue.

    There are a few things you ought to do before getting it "checked". If you were to get it checked, I'd have the alignment checked but do those other things first.

    If I read you right, those 47.5 mpg are in Imperial gallons, right? That would be 39.55 miles per US gallon.
     
  13. uart

    uart Senior Member

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    Hi Lodrun. At motorway speeds the prius fuel efficiency definitely starts to go down, so you should be able to get better FE at lower speeds. Usually I get my best fuel efficiency on quieter rural roads with lower speed limits. Most people can get over 60MPG_UK (50 MPG_US) fairly easily under those conditions.

    Tire pressures of 38/36 shouldn't cause any big MPG hit (as compared with 42/40). Cold weather and short trips are the biggest MPG killer, though I know there's not much you can do about that. The type of tire you use is also important. Make sure you choose a low rolling resistance tire when you replace your OEM tires. What tires (size and brand/model) are you currently running?
     
  14. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    In the US many auto parts store would check the 12 volt battery for free, I do not know about how true that is in the UK. Like any car, the 12 volt battery lasts about 4 years. (yours would be an early failure) Some failure modes in a Prius has the car constantly trying to recharge the 12 volt battery, which is a direct hit of FE, sometimes by 10 MPG.
     
  15. Tideland Prius

    Tideland Prius Moderator of the North
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    38/36 is fine. I used to run that on the factory tyres.

    What are your summer mpg figures? Part of the lower mpg you're currently experiencing can be attributed to:

    - winter fuel blend (less fuel, more additives per litre)
    - cold starts. You said you park outside so your Prius doesn't have the benefit of a warm garage or at least being plugged in to pre-heat the engine
    - short trips. Yes I know it's 10 miles but my commute with our 2005 Prius used to be 15km and even at 0°C, my Prius would never shut down until it's done at least 10kms of bumper-to-bumper driving. This put a HUGE dent in my mpg figures.
    - Heater --> Heat comes from the engine so the engine will continue to idle to provide heat into the cabin if it is warm enough.


    All of the above have a noticeable impact on the Prius. The Prius is a good way of showing just how small changes can affect mpg figures greatly. In a regular car, that might cost you 2 mpg but on the Prius, it'll be more like 6 mpg.
     
  16. ksstathead

    ksstathead Active Member

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    Have you blocked the grill? There are great threads here for both gen2 and gen3. That greatly speeds the warmup which is pretty significant with your shorter drives. Only costs a couple of bucks in pipe insulation.
     
  17. Frayadjacent

    Frayadjacent Resident Conservative

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    You're in England, and Global Warming is in full effect there - snow and record cold temperatures!

    In the winter, your economy WILL SUFFER. While the engine warms up, you will get CRAP for fuel economy. If your commute is short enough that the engine doesn't have enough time to warm up, your trip will be in the CRAP period of fuel economy.

    I watch the histogram while driving my car, and the first 5 or 10 minutes are CRAP, then it climbs up. My commute is about 15 miles one way, so the engine gets warmed up about halfway through, and the last half of my commute is in the low 40mpg range, which is normal for winter in the US.

    Of course, that averages out lower, due to the first few minutes of CRAP economy.

    How far are you driving? How long between trips?

    One thing you might research is blocking the front grille. This can help the engine warm up quicker and retain heat longer in the cold weather. Lots of people use pipe insulation, but there is a company that makes a panel that fits over the lower grille.

    When the weather warms up, you'll see your economy increase greatly.