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Other influences on MPG

Discussion in 'Gen 2 Prius Fuel Economy' started by Pappy, Feb 1, 2006.

  1. Pappy

    Pappy New Member

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    Two issues I haven't seen discussed relative to MPG performance are tires and gas. I mean differences in manufacture, drag coefficient, road or internal friction, etc. for the tire question--not pressure.

    And, could there possibly be a difference from among gas companies, perhaps to do with refining methods that either optimize the Prius engine efficiency, or not? Maybe we need a poll of people getting in the 60 MPG range to see what gas they're using and in what parts of the country. I know that California requires light sweet crude to accomodate its refining methods. Straight from Iraq is good.

    My max after 1800 miles is 44.5, with an average of 39. Live on a hill, city driving, lots of short drives, no highway, very little freeway.
     
  2. skruse

    skruse Senior Member

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    In California's Great Central Valley I use Valero 87 octane regular year round. Earns 60-61 mpg in warm weather, 50-54 during cold weather. Winter days and mornings can be zero visibility ground fog with the MFD showing 34°F. I fill up when the last pip is flashing. The vehicle consistently will only take 8.5 gallons. I do run the heater on low fan on frosty mornings.
     
  3. tomdeimos

    tomdeimos New Member

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    You must have missed all the arguements on these topics right here. You should be able to look up something though.


    Regarding tires, I checked everything I could before selecting tires. I wanted high mpg and I believe I got good tires. The oem tires are good too, at least for mpg.
    From my reading on the web there are some standard ways to make tires that have low rolling resistance. Extra high tire pressures is one way. The sidewalls design too can have an effect. Anything that reduces flexing helps, but also degrades the ride.
    The tires I got are Michelin Energy MXV4 plus, and these remain soft, but have additives that cut the losses when they flex. In general higher speed tires should be low heat generators and therefore better for mileage.

    Then treads that are slicker should cut rolling resistance, which is why the marathoners used pretty worn out tires. A too flexible tread may kind of scuff on the pavement generating heat.

    That's about all I could find. There was a tire rolling risistance rating article too, posted several times, but it is pretty obsolete now, and has not been updated that I have seen for the newer tire models.

    Here's some more info from Google:

    http://tinyurl.com/aja9b

    http://tinyurl.com/caove

    http://tinyurl.com/94tju

    http://tinyurl.com/7a8ke

    Regarding gasoline that too has been even more controversial. I use Shell whenever possible because I get the best mpg with it. Exxon and Mobil are close.
    So that is about all I use.

    I have tried other brands but most are not readily available around where I live. The ones that are have cost me as much as 10 mpg but I can't be sure if it was contaminated fuel at one station or a general problem with the brand. I decided not to risk the mpg loss by experimenting further.

    Many others argue the fuel is all the same from the same tankers, and so you should just buy the cheapest gas.

    Then there are known mpg differences where Ethanol is added to fuels, making fuels in some locations better or worse for mpg.

    Then there are the gasolines that are approved for their detergent additives. Chevron which is not around here was one of the original ones. That list is on the web somewhere. The claim is mos brands do not have enough detergent to keep injectors clean.
     
  4. Ray Moore

    Ray Moore Active Member

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    I have turned many 60+ tanks and almost always turn in 58+ MPG. I only use Chevron gas. I do that because techron is a great detergent additive. Let me tell you a little secret about gas. It's all the same. The additives are the only things that differ. The pipeline that brings gasoline to your city or region pipes it to a distribution center. There you will find all the major and minor brands filling their trucks from the same source but adding different additives. There are not ten pipelines bringing gas from ten refineries owned and operated by ten majors. Choose your favorite additive and buy that company's gas. A clean engine is about all you can do to help your mileage with gasoline. Oh, and use regular octane.

    I replaced the oem tires with another set. I just couldn't mess with success.

    Current tank is at 675 miles at 58.5 MPG. I'll fill up in the morning.
     
  5. hdrygas

    hdrygas New Member

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    Tires and pressure are major factors!! Just do a search on the site. Gas appears to be much less important as long as you stick to Top Tier Gas. I did an experiment with Shell, Chevron, and Union 76 and could see no measurable difference. What I mean is that temperature and other factors masked any differences I can measure.
     
  6. Pappy

    Pappy New Member

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    Then there are known mpg differences where Ethanol is added to fuels, making fuels in some locations better or worse for mpg.

    Then there are the gasolines that are approved for their detergent additives. Chevron which is not around here was one of the original ones. That list is on the web somewhere. The claim is mos brands do not have enough detergent to keep injectors clean.
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    Thanks to all for contributing to this question. I'd sure like to see if you who are getting 60+ can do it with my Prius! 585 miles per tankful? Get outa here! From the comments, I have to assume that my consistent use of Exxon regular and OEM tires are as good as I can do in those departments.

    Yes, I've seen 99 mpg for 5 minute increments, but it's never maintained long enough to get me much over a 40 mpg average for my city driving and hillside living. I get parking exemption at city meters as a compensation, at least for now.
     
  7. SomervillePrius

    SomervillePrius New Member

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    It is hard to keep the MPG over 50 in congested city driving, maybe with your hills it's harder to keep it over 40. Anyway here are my tricks to reach 46.2 in similar traffic (boston) but w.o hills.

    The things I find make a lot of difference is my driving. The trick (easier said then done) is to maintain speed and not go much faster then the average speed. To do this I try to follow the following tricks:

    1) Anticpate stops! As soon as you see a redlight turn you start to coast (eaither regen'ing to lose speed, or Neutral to annoy drivers behind you less). This makes a big differnce
    2) Keep distance to the car in front of you. The more distance you dare to keep the more times you can just let go of the gas instead of braking. Everytime you brake you waste gas! (You used moregas then neccesary to get up to that speed, only to brake).
    3) Don't go faster then the speed limit and even more important don't go faster then the average speed for that time of day. In the morning the average speed is never really more then 25-30mph on a road listed at 35 mph. So I never exceed 30 and find when I do that I still don't loose (many) redlights anyway. Some parts have 25mph speed limit and can be annoyingly slow but the do get great mpg
    4) loose speed going uphill. I try to get up to speed before going up hill and then while going uphill I keep a "constant" mpg reading. This means that I loose speed while going up hill. I try to not loose more then 5 mph (or people might honk). This works for moderate hills. Not sure how well it works for S.F like hills.
    5) I've started to go to work 30 minutes earlier so that there is less traffic on the road.

    I'm not sure these are techniqes for normal drivers but I enjoy playing the FE game! ;-D

    Hope this helps.

    I think that's about

    So that ar my techniqyes
     
  8. Jack 06

    Jack 06 New Member

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    I'd sure like to know exactly what factors/manufacturing materials make tires LRR (low rolling resistance) or not. I'm now running Nokian WRs on my '04, and they're made with silica in the compound, but they're NOT "rated" as LRR that I could find.

    I also wonder what research has been done on the relationship between MPG and road surface. My intuition is that certain kinds of road "finishes", for example, worn, "pebbly" asphalt, or a more "textured" concrete finish (which you sure can HEAR), might cost you an MPG or even two. Also, it makes sense that summer-sun-heated, softened asphalt gives you unnecessary friction.

    Wonder if fresh, smooth, cold asphalt is best? It's the quietest.

    Can anyone point me to research, or do I have to go see Mr. Google again? Perhaps AAA commisioned a study, or the U.S. DOT?