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First 500 miles on my 09 Prius... observation/question

Discussion in 'Gen 2 Prius Main Forum' started by edzinru, Mar 12, 2009.

  1. edzinru

    edzinru New Member

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    Driving highway speeds this weekend using cruise control. Speed limit 55. Set cruise to 62. Going down somes hills my speed might get up to 70 + mph. Never had this problem with another auto. Wondering if anyone else has noticed this with the Prius.
     
    #1 edzinru, Mar 12, 2009
  2. Patrick Wong

    Patrick Wong DIY Enthusiast

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    Yes, because cruise control only controls your minimum speed, not maximum speed. So if you are on an incline and the car is gaining speed due to gravitational pull, cruise control will not take any action to slow the car down.

    If you have not had this problem with another automobile, this is because the combination of wind resistance and drivetrain braking in your other vehicles resulted in sufficient drag to more than offset any vehicle acceleration caused by gravitation pull.
     
    #2 Patrick Wong, Mar 12, 2009
  3. Tideland Prius

    Tideland Prius Moderator of the North
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    It depends. Sometimes, I've had it speed up, other times, I've had it hold the speed and engine brake to slow down (which means if the hill is steep enough, you're gonna gain speed anyway).
     
    #3 Tideland Prius, Mar 12, 2009
  4. magruder

    magruder Average Member

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    I haven't used cruise much, if you switch to B mode will that cancel your cruise? If not, you could use B on steep hills to slow yourself down temporarily.
     
    #4 magruder, Mar 12, 2009
  5. sdtundra

    sdtundra Senior Member

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    As far as I can tell, having driven and had 3 Toyota's with cruise control in our family (04 Avalon, 05 Tundra, 08 Prius) this is a normal thing.

    If I know a downgrade is coming up, I'll cut my speed down a little just so I'm not completely flying at the bottom. i.e. The hill on 163 South into downtown from Clairmont/Linda Vista in SD. If I am cruising at 65, at the bottom with no braking, I end up at 77 or 80. For this, I tried this once...moving to the right, slowing to 55, then as soon as the hill starts, take off cruise control and let it glide down. It usually doesnt get past 70.
     
    #5 sdtundra, Mar 12, 2009
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