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MPG went up in the last 2 weeks. Help me figure out why.

Discussion in 'Gen 3 Prius Fuel Economy' started by Former Member 68813, Sep 16, 2012.

  1. Former Member 68813

    Former Member 68813 Senior Member

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    In the last 2 weeks I get 60MPG (indicated) with ease on my 22 mile round trip all city work commute. The commute is very predictable with the same speeds and driving technique and similar light pattern.

    The thing is, the most part of the summer I had to work hard to get upper 50's on the same commute.

    No, I don't use AC as the temps are mild enough to drive with windows down in early morning and evening.

    There are 2 variables: the ambient temp went down to low 80's rather than high 80's before. You would think higher temp would be better for MPG (without AC), but I do remember the best MPG this time of year.

    Second, I'm running Techron treatment in this gas tank and it's almost over. I use almost always Chevron/Texaco gas, so the injectors should be clean, but I hear that 20,000 miles is the point where cleaning is usually helpful.

    So, what is it: lower temps or injection cleaning?

    Edit: today was a good example of the improvement. I hit 60MPG on mile 7 and by the time I finished the trip, it was slightly over 60MPG. Previously I would hit 60MPG not sooner than 10th mile or so.
     
    #1 Former Member 68813, Sep 16, 2012
  2. JimboPalmer

    JimboPalmer Tsar of all the Rushers

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    Maybe it is so much milder you don't have the windows down, so are getting better aerodynamics?
     
    #2 JimboPalmer, Sep 16, 2012
  3. Former Member 68813

    Former Member 68813 Senior Member

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    I thought about it, but I use rolled down windows in PM on return trips but not in AM, no difference between then and now.
     
    #3 Former Member 68813, Sep 16, 2012
  4. MarvHein

    MarvHein Junior Member

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    Tires more worn or did you change the inflation?

    I finally hit over 60 mpg my last two tanks in my 2010 before turning it in at end of lease, am improvement coming from extremely limited use of A/C and cabin fan. I am struggling to get there again with my new 2012. 58 mpg the first tank and settling in around 56 mpg halfway through the second tank. Tires inflated to 40 psi on both cars. But the tires on the 2010 were pretty low on tread while the 2012 's are, of course, new. I seem to recall my tires wearing out quite rapidly in the 20's with my 2010.... which sounds like where you are now from your comment about the injectors.
     
    #4 MarvHein, Oct 10, 2012
  5. Selzier

    Selzier Whee!

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    How many miles are on your car? I hear that there is some benefit to the cleaning but there is also a break-in period. Some posts I've seen had people gaining MPG's after 5, 10, and 20 k intervals.

    Also, have you switched your driving modes between eco, normal, and power? These styles I noticed lend themselves better to certain people (as I actually get MY best mileage in normal mode while my girlfriend gets the best mileage in eco mode.)

    Another factor is you may have adjusted to the driving style of your Prius. I forgot where I read it but one hypermiler's tip was to not even worry about getting max mpg when you first own the vehicle. Drive it how you want, and the learning will come. This is also true for me as my first 2-3 k miles were getting me roughly 48-49 mpg and then lately I've jumped up to about 54-55.
     
    #5 Selzier, Oct 10, 2012
  6. Former Member 68813

    Former Member 68813 Senior Member

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    1. Over 20,000 miles.
    2. Normal mode only.
    3. I have been driving my prius for over 2 years and figured out the P&G in the first month and no changes since.

    After driving some more in the 60-80 temps rather than 80-90F, I can tell for sure there is a better fuel efficiency at these lower temps. Again, I usually don't use AC even in summer and drive with rolled down all windows when hot and dry (this is all city driving). I guess rolled down windows give some MPG penalty, but I'm still surprised.

    I don't think anymore it was an injector cleaner, as I remember now the same observation one years ago as well as 2 years ago when we transitioned from summer to fall. Obviously MPG will plummet in winter.
     
    #6 Former Member 68813, Oct 27, 2012
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