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Motorcyles good for your Prius Mileage ?

Discussion in 'Gen 2 Prius Technical Discussion' started by donee, Jun 29, 2006.

  1. donee

    donee New Member

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    Hi All,

    I was drafted by a Motorcyle this morning while I was in cruise control on the way to work this morning. I looked up and saw him sneak up while watching the MFD mileage. It was difficult to be sure, but it sure seemed like when he got about 2 feet back the mileage went up by about 5 mpg. This was at 65 mph. When he pulled to the right and went around, the mileage seemed to get worse by 5 mpg!? this was all on the same nearly level stretch of road.

    Wierd.

    There might be some aerodynmic improvement yet to be had in the Prius design, it seems!
     
    #1 donee, Jun 29, 2006
  2. brandon

    brandon Member

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    Uh, were you looking at the instantaneous MPG reading? That's a terrible way to judge actual fuel efficiency. You need an average over a reasonable distance of consistant terrain and environmental conditions if you want to judge something like that.
     
    #2 brandon, Jun 29, 2006
  3. benighted

    benighted New Member

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    I've noticed that the current MPG drops when somone follows closely too.
     
    #3 benighted, Jun 29, 2006
  4. auricchio

    auricchio Member

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    And when the motorcycle stops suddenly, you'll kill the rider. A cycle can stop much more quickly than a car.

    Anyone who tailgates a motorcycle is an idiot.
     
    #4 auricchio, Jun 29, 2006
  5. jonlink

    jonlink New Member

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    <div class='quotetop'>QUOTE(Rick Auricchio @ Jun 29 2006, 06:41 PM) [snapback]278833[/snapback]</div>
    While you're correct, you didn't read the post. The motorcycle was drafting HIM.
     
    #5 jonlink, Jun 29, 2006
  6. Tideland Prius

    Tideland Prius Moderator of the North
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    He could be dissipating the turbulence behind you. If you look carefully at newer cars (I'll use the new Lexus IS for this example), take a look at their rear taillight assembly. The IS has a tiny piece that juts out at the corner so that the air doesn't stream around the back of the car but continues straight on.
     
    #6 Tideland Prius, Jun 29, 2006
  7. donee

    donee New Member

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    <div class='quotetop'>QUOTE(Tideland Prius @ Jun 29 2006, 09:21 PM) [snapback]278883[/snapback]</div>
    Hi Tideland,

    The motorcycle was all the way left when he was drafting me, so that his flank was in-line with the left side of my car. So, that could be the reason. Interesting...



    <div class='quotetop'>QUOTE(Rick Auricchio @ Jun 29 2006, 07:41 PM) [snapback]278833[/snapback]</div>
    Hi Rick,

    Just to confirm that you did not read my post correctly, as another already has. The Motorcycle rider was behind the left side of my car, peaking up over my rear view mirror at the road ahead.
     
    #7 donee, Jun 29, 2006
  8. auricchio

    auricchio Member

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    Forgive me. I blew the basic requirement of actually reading what you said.

    Now that I've actually given this some thought, I agree that it's possible the bike was helping to "break" the air ahead of the two of you, cutting a little drag.
     
    #8 auricchio, Jun 29, 2006
  9. jmccord

    jmccord New Member

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    <div class='quotetop'>QUOTE(Tideland Prius @ Jun 29 2006, 07:21 PM) [snapback]278883[/snapback]</div>
    Aerodynamics and air resistance is a huge issue. Things like you mention can easily affect noticeable changes in MPG.
    For every mile down the freeway, the average-size American car has to push 5.5 metric tons of air out of its way. In fact, at 70 miles (110 kilometers) per hour, the typical highway speed, as much as 65 percent of the fuel the car uses goes to overcoming air resistance.

    For more on how vehicle mileage is affected and some interesting reading on tractor trailer wind wakes, check out the following link:
    http://www.llnl.gov/str/May03/McCallen.html
     
    #9 jmccord, Jun 29, 2006
  10. NuShrike

    NuShrike Active Member

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    <div class='quotetop'>QUOTE(Rick Auricchio @ Jun 29 2006, 03:41 PM) [snapback]278833[/snapback]</div>
    RTFA. If he braked hard, he could kill the rider anyways... Just like some black truck tried on somebody I know and spilled him into the fast lane. Stopping power is little help for sudden steering/maneuvering stability.
     
    #10 NuShrike, Jun 30, 2006
  11. donee

    donee New Member

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    <div class='quotetop'>QUOTE(NuShrike @ Jun 30 2006, 05:38 PM) [snapback]279297[/snapback]</div>
    Hi Nushrike,

    Yea, I agree completely. It was lucky for this guy I was in cruise control and all the control ripple had settled out. The Prius does not give good aural feedback as to how fast you are going like other cars. The Prius engine speed varies widely with throttle position, and its not hard linked at all to vehicle speed. If I would have been controlling the throttle myself, it would have been a much more dangerous situation.
     
    #11 donee, Jul 1, 2006
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