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So close and yet so hot

Discussion in 'Gen 2 Prius Fuel Economy' started by TonyPSchaefer, Aug 3, 2007.

  1. Saguaro

    Saguaro New Member

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    It's just the way I roll; it's the game I play.
    [/quote]

    I'm with you Tony. I've been driving without A/C here in Phoenix, Arizona the last month and I've been able to keep my mileage signifigantly higher (59.0 MPG). In fact, my last fill-up was July 2nd, over a month ago. I have never gone that long between fillups before. I'm going for my first 60 MPG tank so I can't blow it now by turning on the A/C! It helps when the outside temperature is 90 degrees at 8:00 am at startup - I get to stealth mode real quick.

    My wife thinks I'm crazy for driving with the windows down (especially when it's 115 in the afternoon) but I don't care! I'm still trying to figure the car out and see what it's capable of. Phoenix is actually pretty ideal for the Prius - relatively flat terrain, mild temperatures (most of the year).

    I love my Prius!
     
  2. TonyPSchaefer

    TonyPSchaefer Your Friendly Moderator
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    Wow, Hobbit. I had that exact thought on my way home tonight. Mainly because of this thread and the discussion of battery heat. I was wondering why the battery vent is in the cabin whereas in the classic it's on the outside. Right? I mean, I assume that's what the vent on the side of the classic is for.

    The actual thought I had was to connect a shop-vac hose from the far-right dash vent straight back to the battery vent. But that's a little too extreme for me. Let me know how it works out for you though. ;)

    When wanting to cool the pack, would it be prudent to roll the back passenger window down all the way to get the most air possible into that vent?

    [inside reference: you've inspired me to make my own wooden gazebo reinforcements. I'll test them next weekend]
     
  3. paulccullen

    paulccullen New Member

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    <div class='quotetop'>QUOTE(paulccullen @ Aug 3 2007, 07:58 AM) [snapback]489916[/snapback]</div>
    Um. TYPO. I meant MPG.

    I'm wondering if "hypermilers" are annoying other drivers and giving the Prius a bad image as a slow pokey car. In order to get 60+MPG you'd have to be moving and accelerating *really* slowly. Fortunately Al Gore III may have counteracted that image a little.

    I drive at the ambient traffic speed (and use the A/C when it's warm), and manage to get *only* 50-51MPG (less in winter)

    But Tony's comparison to arcade games is a good one. We all get a little obsessive/compulsive over things...
     
  4. usbseawolf2000

    usbseawolf2000 HSD PhD

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    I experienced the same behavior last Thurs trip back home. It was 95 deg outside (according to MFD) and I couldn't glide. This was after 25 miles drive. I had the same thought as Tony so I turned the AC on and pointed the passenger side vent upward to the roof. After a few minutes, I was able to glide. When I got home, MPG for that 44 miles commute was 66.6 MPG. It was a record for me.
     
  5. hobbit

    hobbit Senior Member

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    ..."you'd have to be moving and accelerating really slowly"
    Completely incorrect. One in fact wants to be reasonably brisk on
    the acceleration side to run the engine efficiently. What might be
    a little different is the optimal *timing* of when you do it, i.e.
    leaving more of a gap ahead before deciding to do your "burn". This
    may give the impression of "pokey" to people who just don't understand,
    but quite normal acceleration with the right timing and duration
    still yields satisfyingly high MPG. Deceleration is also when the
    significant gains happen if one does so smoothly and from reasonably
    far out, to maximize regenerative recovery -- which given how far
    too many people have conditioned themselves to drive, may also be
    thought of as "pokey" but loses absolutely nothing in terms of time
    spent at a red light.
    .
    But steady-state speeds are entirely normal and on par with everyone
    else around, except perhaps on freeways where a nominal travel rate
    of 60-65 yields good MPG performance and the clowns doing 85 might
    view that as "slow". But it's certainly not just hybrids doing that;
    consider trucks, RVs, rattletrap farmer pickups, and people who want
    to avoid that v^3-proportional MPG hit. So don't call it "pokey" in
    a blanket fashion until you really understand what's going on.
    .
    _H*
     
  6. bwilson4web

    bwilson4web BMW i3 and Model 3

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    <div class='quotetop'>QUOTE(hobbit @ Aug 3 2007, 09:36 PM) [snapback]490307[/snapback]</div>
    I've been thinking along the same lines and how a foam and fiberglass hood and trunk lid might accomplish this goal. It would be easy enough to make a foam and glass fiber mold and then build up a composite structure.

    My thinking is a clear, thermal plastic could be vacuum formed over the mold for the outer surface. Then a layer of pipes/channels built up followed by a carbon fiber and foam structure to mechanically hold the assembly. Making it look pretty would be a challenge but it should capture a lot of solar heat.

    Bob Wilson
     
  7. MaxLegroom

    MaxLegroom Junior Member

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    <div class='quotetop'>QUOTE(paulccullen @ Aug 4 2007, 11:35 AM) [snapback]490510[/snapback]</div>
    Some hypermilers may indeed be annoying to other drivers. Right now, I've an average of 61mpg on the current tank. I didn't get it by moving really slowly, but a lot of my driving was in Sandbridge in Virginia Beach, and I seemed to be moving between recharging and EV a lot. Thing is, I didn't lose much of the average I had there driving across Norfolk, Portsmouth and Suffolk. Actually, at the end, someone in a Neon coupe wanted to show his buddies how fast he was by burning the 35th St. offramp, only to find himself stopped at the next light, which is where I caught up to him. When he blasted off from the light, I glued the Prius to his rear bumper, kept with him through the next corner, and pulled next to him at the next stop sign. He (and his buddies) slinked off to the left, and as I glided into my parking space, the MFD read an average of 61.0mpg. While the last is actually unusual for me with the Prius, once in a while, an opportunity too good to pass up shows itself. A more usual style is for me to drop back a bit. Between gliding up to lights and keeping an eye open I usually am passing other traffic in the city.

    I use the A/C all the time. Just because I came back from Kuwait six months ago doesn't mean I like the heat, and my Prius is black.

    Tony is spot on with the arcade analogy. It is like playing a video game. The Prius even steers like one, especially compared with my old Sebring, which had steering that talked more than a Hollywood insider.
     
  8. jdenenberg

    jdenenberg EE Professor

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    <div class='quotetop'>QUOTE(Danny Hamilton @ Aug 3 2007, 11:16 AM) [snapback]489921[/snapback]</div>
    Danny,

    The Grid may be cheaper, but it is not more efficient. The typical efficiency of electric power is about 25% from the fuel to the home. Then you have to take into account the efficiency of the using appliance.

    There are two reasons for the price differential. First is that the utility has the benefit of "economy of scale". The second is that you are sidestepping "road use" taxes (may be a temporary situation).

    Just keep these factors in mind when considering the use of generated electricity to replace direct use of gasoline/diesel fuel in transportation.

    Jeffd
     
  9. Danny Hamilton

    Danny Hamilton Active Member

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    <div class='quotetop'>QUOTE(jdenenberg @ Aug 8 2007, 09:47 AM) [snapback]492371[/snapback]</div>
    I haven't seen any studies yet. How efficient is the Prius from fuel to battery?

    There is also the matter of what is meant by efficiency.

    As one example, although it would be a bit redundant in my original comment, efficient might mean "most efficient use of my money", in which case use of the grid is a more efficient "pocketbook to battery" path than use of gasoline.
     
  10. JackDodge

    JackDodge Gold Member

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    <div class='quotetop'>QUOTE(TonyPSchaefer @ Aug 3 2007, 08:40 PM) [snapback]490237[/snapback]</div>
    There is some UV protection, sure, but not enough for my preferences. I have the sun on my side of the car going to the office and on the way home so I got tinting and it seems to make a significant difference. They keep the office building at 65 during the summer so when I get in the car to go home, I just luxuriate in the heat for the first ten minutes and then turn on the A/C. I've not had the heat problem that you describe so perhaps the tinting helps? Thanks for the insight though, I'll remember that if I ever get a strange issue with MPG when it's hot outside.