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Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerator?

Discussion in 'Gen 3 Prius Main Forum' started by cycledrum, Feb 27, 2010.

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Does your 2010 roll backwards about 1ft/sec in D gear on incline, from a stop?

  1. Yes, from a stop, foot off brake, accelerator, car rolls back a lot, maybe 1 ft/sec

    13 vote(s)
    52.0%

  2. No, the car does not roll back much on an incline, maybe 1 in/sec

    12 vote(s)
    48.0%
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  1. cycledrum

    cycledrum PSOCSOASP

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    ** Note - rate of rolling backwards was same for me on gentle and steep slope **

    I've seen another thread from 2007 about a Gen2 rolling backwards in D gear at a stoplight.

    Here's the facts I've seen -

    I rented a 2010 Prius III. In my driveway, which has a mild slope (maybe 8" drop over 8 ft), the car rolled backwards repeatedly at 1 ft./sec. (that's a lot), foot off brake and off accelerator. I let the car roll back about 6ft.. Same rate of rollback on a gentle incline or steeper hill.

    My 2009 Prius does not rollback much at all. Maybe 1 inch/second max.

    So, does this mean with a 2010 Prius, leaving a stoplight up a hill in San Fran, the car will roll back by the time you move foot from the brake to accelerator, then need accel. to get the car moving forward again?

    Or, one is supposed to be lightning quick moving foot from the brake to accelerator?

    ???
     
    #1 cycledrum, Feb 27, 2010
  2. Paradox

    Paradox Prius Enthusiast / Moderator
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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    If you press the brake pedal hard while stopped on a hill, it activates the hill start feature. It gives you time to transition from brake to gas and keeps the car from rolling backwards. All 2010's have this feature.
     
    #2 Paradox, Feb 27, 2010
  3. hsiaolc

    hsiaolc New Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    The poll is a bit misleading I thought. The roll back all depends on the angle of the incline.
    At steep angles then yes it will roll back heavily but on a less angle incline, the car doesn't roll back at all but if you feel the roll back will happen then put the car in hill assist mode like one mentioned earlier.
     
    #3 hsiaolc, Feb 27, 2010
  4. adamace1

    adamace1 Senior Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    Thats why the car has "HILL ASSIST". But mine does roll backwards just like my 04 impala did.
     
    #4 adamace1, Feb 27, 2010
  5. john1701a

    john1701a Prius Guru

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    That's an odd question to ask, since the neither the steepness nor the distance actually rolled back is mentioned.

    A better question how long it takes for new owners to discover the Brake-Assist feature.
    .
     
    #5 john1701a, Feb 27, 2010
  6. 32kcolors

    32kcolors Senior Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    All cars roll back on a steep enough hill. On a slight incline, it doesn't roll back at all.
     
    #6 32kcolors, Feb 27, 2010
  7. lunabelgium

    lunabelgium Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    I never tested very strong inclined, so still now it's NO.
     
    #7 lunabelgium, Feb 27, 2010
  8. spiderman

    spiderman wretched

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    Interesting though... if the Gen 2 did not(much), why did they make the Gen 3?
     
    #8 spiderman, Feb 27, 2010
  9. hobbit

    hobbit Senior Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    This is one of the real misfeatures of the third-gen. In the
    second-gen, the hybrid ECU could easily determine that MG2 was
    starting to spin backwards, and simply apply just enough current
    to make fairly strong counter-torque -- not enough to take off,
    but enough to let the car roll backward *very* slowly in a
    controlled fashion. Plenty of time to transfer a foot to the
    go-pedal and ask for more torque and get going. In the third-gen,
    they've trashed this completely sensible methodology and gone
    with this extra "hill assist" nonsense that drivers have more
    trouble figuring out and requires extra steps to invoke.
    .
    One of the backward steps in the "evolution", if yer asks me.
    .
    _H*
     
    #9 hobbit, Feb 27, 2010
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  10. mad-dog-one

    mad-dog-one Prius Enthusiast

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat


    Mine, and I thought all of the Gen IIIs, has got a hills top feature that prevents rolling for a couple of seconds after pushing moderately hard on the brake pedal.
     
    #10 mad-dog-one, Feb 27, 2010
  11. ggood

    ggood Senior Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    How much is too much or too little assist? Some people prefer no artificial assist at all. God forbid there be any unintended acceleration!
     
    #11 ggood, Feb 27, 2010
  12. fuzzy1

    fuzzy1 Senior Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    ???

    The rollback is slower than the rollback of our stick shift cars. Because the last traditional automatic left this household a quarter century ago, I can't accurately compare the Prius to them.

    Being habituated to clutches, I haven't bothered to use the Prius Hill Start Assist. And based on the owner's manual description, it isn't as good as the version in recent sponsor Subarus I've driven for events. Tap the brakes for a moment, and they prevent rollback until some forward motion is achieved. There is no time limit, at least that I found.

    But I'm not replacing my old stick shift Subaru until the new ones contain HSD.
     
    #12 fuzzy1, Feb 27, 2010
  13. cycledrum

    cycledrum PSOCSOASP

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    Thanks you two. I highlighted my post stating it's the same on gentle or steeper slope.

    Rental car had no owner's manual onboard, and I did not know about hill assist (wonder if my 09 has that, hmmm).

    Obviously I didn't hit the brake hard enough in the driveway.

    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat



    1) It was a rental car, no owner's manual provided.

    2) I mentioned the slope of my driveway. The hill was probably a 4ft rise over 10ft. I let the car roll backwards at least 8ft. while estimating the rate. It would have rolled back indefinitely.

    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    Like said before, seems I didn't hit the brake pedal hard enough ...

    The car rolled back ~1ft/sec on an 8" / 8ft slope (that's mild!) all the way down the driveway.

    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    Ok, so I learned something.

    I asked 3 salepeople about this rolling back while having my 09 serviced this morning (it was a zoo with all the recalls!!). ..

    none of them knew the answer. Not one mention of hill assist. That's a shocker. :rolleyes:
     
    #13 cycledrum, Feb 27, 2010
  14. jburns

    jburns Senior Senior Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    Not lightning quick but if it takes you a full second to move your foot from the brake to the gas you shouldn't be driving in the first place. Its a non issue as far as I can see although the generation II had a simple solution to limit rollback.
     
    #15 jburns, Feb 27, 2010
  15. ItsNotAboutTheMoney

    ItsNotAboutTheMoney EditProfOptInfoCustomUser Title

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    I've noticed that it will roll backwards on a hill, but I consider that normal since when I first learned to drive it was in a car with a manual transmission. (I'm from the UK.)

    I just move my foot lightning fast from brake to gas pedal. ;)

    If I were on a steep hill with somebody really close behind me I 'd use the parking brake. (I'd normally call it the hand brake but it's a pedal.)

    In fact, on the DVD you get with the 2010 it tells you to use the parking brake whenever you come to a stop and then explains the standard hill start procedure. That's consistent with how I learned to drive: I was taught to use the hand brake whenever I stopped.
     
    #15 ItsNotAboutTheMoney, Feb 27, 2010
  16. cycledrum

    cycledrum PSOCSOASP

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    Ok.

    I tested the rental 2010 on a fairly steep hill, actually upper part of Appian Way in Union City, CA. The incline is roughly 4 ft gain over 10ft.

    I stopped on the hill. Held right foot on brake. The instant I released the brake, the car began to roll back. I did get on the accelerator quickly, while the car rolled back maybe half a foot, then gassed to get car moving forward again.

    Next time I'll try the hill start assist.
     
    #16 cycledrum, Feb 27, 2010
  17. Paradox

    Paradox Prius Enthusiast / Moderator
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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat


    Hard enough until you hear a beep and the hill start assist light lights up on the dash. Just press hard on the brake pedal like your pressing hard on the emergency brake with your left foot to set the emergency brake...
     
    #17 Paradox, Feb 27, 2010
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  18. fuzzy1

    fuzzy1 Senior Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    For automatics without Hill Start Assist (i.e. not Prius or some Subarus) and no hand lever for the parking brake, this is where you can switch to left foot braking.

    Just don't start a left-foot habit the rest of the time.

    I hope that when runaway cars are prevented by programming the brake to shut down the throttle, that either HSA is always added or the programming allows left-foot braking to assist uphill starts.
     
    #18 fuzzy1, Feb 27, 2010
    rsgillmd likes this.
  19. hitechboy

    hitechboy New Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    The only brand of automatic car that doesn't roll back is Mercedes (of all the different brand of car that I have own). So if you don't know how to use the hill start assist feature, you know what to buy next time.:D
     
    #19 hitechboy, Feb 27, 2010
  20. bebe

    bebe New Member

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    Re: Does your 2010 Prius roll backward at 1ft/sec in D gear on an incline, foot off brake, accelerat

    I HAVE a 2007 Prius with the same problem.
    When I have to stop on a hill and then start, I roll backwards at an alarming speed before I accelerate. I have tried using the brake and accelerator pedal at the same time but there is a built in "safety" feature which prevents this from happening. The forward motion is cancelled. I have been in a tough situation on a very steep grade where I had to have my passenger jump out and place a rock under the rear wheels to prevent the roll back into a steep drop off. I was then able to activate the accelerator to continue up the hill. I am now afraid to drive up steep hills, if I may have to stop half way up.
    Toyota says it is normal because the car is electric and gas and the electric motor with front wheel drive will not have enough power to accelerate without going backwards first.
    This to me is unacceptable!
    I would like to hear comments from others.
    bebe
     
    #20 bebe, Mar 9, 2010
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