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55-60 mpg @ 60. 46-50 mpg @ 70

Discussion in 'Gen 3 Prius Fuel Economy' started by franktsay, Jan 22, 2010.

  1. franktsay

    franktsay New Member

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    my friends:

    This is my second posting here. I got my new 2010 Prius, package III, on 10/16/2010. The accumulated mileage is now over 12500. Got two oil changes at a Toyota dealer. Getting the third soon. I live in Long Island, having one of the worst winters and definitely the worst snow storm in Long Island history.

    I drive 185 miles+ a day, 5 days a week, and less for the remaining two days in a week. 80% of that 185+ miles is on highways. For the remaining two days, mostly local.

    After trying every different way of setting and driving, my conclusion is that speed alone is the most important factor that affect your mileage.

    I used to drive at 70    +-5 MPH .(Don't tell anybody. The speed limit is 55.) I got 19.7 MPG with my previous car, Infiniti M35X. With this new 2010 Prius, I have been able to get somewhere between 46 and 50. Quite an astonishing improvement already. However, some of you guys' postings still made me extremely jealous.

    Getting into the new year, 2010, I decided to become a more responsible driver, driving closer to the speed limit, getting less speeding tickets, and seeing more middle fingers from some of those guys passing me. No matter what, I am determined to drive at the speed of 60+-5 MPH.

    Voila! Now I constantly get 55-60 MPG! I am saving roughly $5500 of gas annually instead of previously estimated $4500-$5000 a year! If I can keep this car for 4 years, the car is virtually free! I am not even counting the extra expenses caused by speeding tickets. I might be able to worry less about my hypertension and live a bit longer and healthier due to less stress driving slower.

    Did I lose anything? Yes, 10 to 15 minutes a day out of that 185+ miles of driving. However, I might be able to live longer to compensate that loss.

    I feel really good and want to share my experience with all my friends here.

    Happy driving!

     
    #1 franktsay, Jan 22, 2010
    5 people like this.
  2. ksstathead

    ksstathead Active Member

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    Congrats. Wish I could match your mpg, but driving 3.2 miles/day + side trips and highway trips once a month, I will live in envy. Have to guess you run above placard tire pressures? Even so those are great numbers in the winter. You must have good technique for the Prius. Keep up the good work.
     
    #2 ksstathead, Jan 22, 2010
  3. qbee42

    qbee42 My other car is a boat

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    Speed is indeed one of the main factors in mileage. Another major factor is trip length. Short trips are mileage killers, and there isn't much you can do about it.

    As for speed, the power required to move a car through air goes up by the cube of the speed. Think about what that means: to go three times as fast you need 27 times the power.

    For a fixed length trip you get there faster by driving faster, so the energy required to drive the trip goes up by only the square of the speed: 9 times the energy to drive three times as fast.

    These figures are only for ideal aerodynamic drag. Other factors come into play, such as engine efficiency at various power outputs. Any way you look at it, speed is a mileage killer.

    Tom
     
    #3 qbee42, Jan 22, 2010
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  4. usbseawolf2000

    usbseawolf2000 HSD PhD

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    It is great to see someone from Long Island. I assume you commute on LIE (I-495).

    I have discover the same thing myself, taught by Prius.

    Your insurance will get lower too due to less moving violations. Take defensive driving course to take additional 10% off from insurance.
     
    #4 usbseawolf2000, Jan 22, 2010
  5. kgall

    kgall Active Member

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    Frank,
    Welcome to the club!
    BTW, how did you get those mileage numbers? Did you accept what the car's MPG/trip computer is telling you, or do the math based on gallons of gas you put in the car? The bad news is that for many Priuses, the computer is about 5% high.
    But even if you lower your numbers that much, you are still doing real well.

    Happy driving!
     
    #5 kgall, Jan 22, 2010
  6. franktsay

    franktsay New Member

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    Kgall,

    It was based on the trip computer. I noticed the discrepancy right after getting the car. However, after a few tanks, I no longer calculate the actual MPG myself.

    I cannot wait to see the mileage in warmer seasons. Maybe 5% or even 10% better? Hehe.

    Oh, by the way, my tire pressures are set to factory recommendation. Just do not want to lose any traction by over-inflating, especially in winter.
     
    #6 franktsay, Jan 22, 2010
  7. franktsay

    franktsay New Member

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    Hi Tom,

    Thanks for the knowledge. Now I have some more thing to impress my wife and friends.

    Frank
     
    #7 franktsay, Jan 22, 2010
  8. ken1784

    ken1784 SuperMID designer

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    :welcome:
    It meets our observation, 60 mpg @ 60 mph rule.
    I wonder if you were very rich driving wonderful Infinity and paying huge gasoline bill before. :)
    I'm jealous you are getting Prius for free in four years.
    I only drive 10k miles per year.

    Ken@Japan
     
    #8 ken1784, Jan 22, 2010
  9. Judgeless

    Judgeless Senior Member

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    Make sure your Tires are at 42-44 PSI. That will improve MPG's alot.

    I drive 30,000 miles a year. Since yesterday I put 100 miles on at an average 62MPG. That is 100% highway. It will go down this weekend with alot of stop and go.
     
    #9 Judgeless, Jan 22, 2010
  10. Creaky

    Creaky Still motorin...

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    #10 Creaky, Jan 22, 2010
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  11. oxnardprof

    oxnardprof Member

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    You experience matches mine. I drive 60 to 65 mpg, and my fuel efficiency improved. In my case, I have to deal with some grades on the commute, so one direction is much better MPG than the other. It averages out to above 50 mpg highway.

    In city traffic, I never get the best fuel efficiency, which I attribute to shorter trips, since all my close to home driving involves trips less than 30 minutes in length.
     
    #11 oxnardprof, Jan 22, 2010
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  12. SageBrush

    SageBrush Senior Member

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    Congrats on joining the club, grandma ;)
    60 mpg continues to give me a warm fuzzy feeling, even after 5 years of Prius driving.
    Not 59.9.

    60
     
    #12 SageBrush, Jan 22, 2010
  13. franktsay

    franktsay New Member

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    I already got it. Thank you very much! With the sticker, I save about 30 minutes of driving time per day! This is one of the two major reasons I bought the car. The other one is, of course, the excellent fuel economy.
     
    #13 franktsay, Jan 22, 2010
  14. kgall

    kgall Active Member

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    I am starting to think that 46-50 at real 70 mph (which I take it is about 72 on the speedometer--speedometers read high to discourage us from speeding) is a bit high--I seem to be closer to 44-45 when I cruise at that speed, even after warmup --making the assumption that the 5 minute bars read about as high as the computer generated trip MPG--i.e., about 5-6 percent.
    On the other hand, when I cruise at 60, using the same estimates, I do seem to be in the 55-60 mpg range.
    The problem is that the cruise period of driving isn't all that we do. Particularly, the warmup period really brings things down, as do steep hills, which I have several of, even though they are not the great hill roads of the west (e.g., the 1800 ft. elevation change between Moscow and Lewiston, Idaho, which many folks I know commuted--my commute out there, before the Prius, was up and down 400 ft each way).
     
    #14 kgall, Jan 27, 2010
  15. F512M

    F512M Member

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    Congrats on your mileage!!!
     
    #15 F512M, Jan 29, 2010
  16. shankyyy

    shankyyy Member

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    hey guys,

    I'm surprised at the high mileages at freeway driving (60@60, and about ~45@70). If that is the case, the mileage should be even better at stop and go traffic because of the battery kicking in frequently compared to on freeways or ???
     
    #16 shankyyy, Jan 31, 2010
  17. ken1784

    ken1784 SuperMID designer

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    My best segment at flat stop and go city driving is 97.2 mpg (41.3 km/L).
    Such kind of mpg is not possible at flat freeway (above 45 mph) driving.

    Ken@Japan

    [​IMG]
     
    #17 ken1784, Feb 1, 2010
  18. franktsay

    franktsay New Member

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    No, shankyyy. Stop and go does not generate the best mileage. My experience is that the best mileage without help from elevation difference comes from slow but constantly moving between 40 and 50 traffic. You could achieve 60+ that way without much difficulty.
     
    #18 franktsay, Feb 3, 2010
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