1. Attachments are working again! Check out this thread for more details and to report any other bugs.

Maintaining CC set speed in the mountains

Discussion in 'Gen 3 Prius Technical Discussion' started by jdcollins5, Nov 13, 2009.

  1. jdcollins5

    jdcollins5 Senior Member

    Joined:
    Aug 30, 2009
    5,131
    1,340
    0
    Location:
    Wilmington, NC
    Vehicle:
    2010 Prius
    Model:
    III
    I have a friend of mine that lives in the mountains of NC and was riding in my car the other day. He asked me how the Prius did maintaining CC set speed in steep mountain down grades with the regenerative braking and B mode engine braking. For those of you that live in the mountains, does the Prius maintain set CC speed better than other vehicles?
     
    #1 jdcollins5, Nov 13, 2009
  2. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    45,024
    16,242
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Apparently it does on the 2010. The only time it couldn't hold the speed was on the steepest descent now the side of the coastal mountains (don't know the grade but that stretch of road is basically straight up and straight down the other side, there's no flat area where you "step" your way up or down). Even through the Rockies, it held the 110km/h speed limit down the hill. I'm impressed. Besides, why wouldn't you let the car roll down the hill anyway (unless there's a known speed trap)


    The Gen 2 holds it but it seems to be pickier as we've had several threads from owners who complained that the CC never held its speed down a hill. Mine always did.
     
    #2 Tideland Prius, Nov 14, 2009
  3. Judgeless

    Judgeless Senior Member

    Joined:
    Jun 30, 2009
    1,821
    256
    0
    Location:
    Cleveland, OH
    Vehicle:
    2010 Prius
    Model:
    IV
    The Prius Gen III does a good job. I drove from Ohio to Key West FL through Virginia and West Virginia. It would never get below or above 4 MPH from what I had it set for. I let the car do all the braking using regenerative braking and it worked well.
     
    #3 Judgeless, Nov 14, 2009
    1 person likes this.
  4. jdcollins5

    jdcollins5 Senior Member

    Joined:
    Aug 30, 2009
    5,131
    1,340
    0
    Location:
    Wilmington, NC
    Vehicle:
    2010 Prius
    Model:
    III
    He lives in Beach Mountain, NC (right outside of Boone) and the reason for not rolling down the hill is there are speed traps. Appalachian State University is in Boone and the school kids love to build up speed coming down the mountain !! My son went there and said he was the only one that he knew that did not get a speeding ticket !

    There are two steep down grades coming down the mountain, with runaway truck ramps. If you do not downshift or use brakes, you can get up to 80 to 90 mph and it is only a 55 mph speed zone.
     
    #4 jdcollins5, Nov 14, 2009
  5. tumbleweed

    tumbleweed Senior Member

    Joined:
    Oct 3, 2005
    4,067
    688
    0
    Location:
    Eastern Oregon
    Vehicle:
    2010 Prius
    Model:
    V
    I agree with the others, it does a great job. Sometimes to good, if I have a full battery (6 bars or more) and I'm not afraid of getting a ticket I cancel the CC coming down hill so I don't waste the velocity. This car will coast a log way and the HSI makes it easy to keep in "warp stealth". Lots of fun!.
     
    #5 tumbleweed, Nov 14, 2009
  6. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    17,557
    10,324
    90
    Location:
    Western Washington
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I'm more worried about adhesion limits on corners, and rear-ends of traffic ahead.

    Downhill CC works very well for me when the traction battery is not full. When it fills, the screaming compression of the engine can exceed my tolerance, so the friction brakes get some use.

    I have never tried downhill CC on a pre-hybrid.
     
    #6 fuzzy1, Nov 14, 2009
  7. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    45,024
    16,242
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Ahh, I see. The other option (if you don't want to ride the brakes), is to shift into B. The engine will rev (engine braking).

    Adhesion isn't a problem. I let the car roll down the side of the mountain and cornering wasn't an issue (15" tyres).
     
    #7 Tideland Prius, Nov 15, 2009
  8. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    17,557
    10,324
    90
    Location:
    Western Washington
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Did your airbags fire?

    I'd rather stay on the road, where corning remains an issue, than fly off the bank and roll down the side of the mountain. Those big trees can slice the car in half, and those cliff drops are a long way down.
     
    #8 fuzzy1, Nov 15, 2009
  9. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    45,024
    16,242
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    ............

    I'm sure any mountain road with a 110km/h speed limit doesn't have sharp corners. The one with sharp corners has a 25km/h limit and it's literally a 90° left-right switchback (about 14 of them). Now that's scary even at at 25km/h. Ahh.. our beautiful cross-country highway.


    You really have no trust in modern technology (I'm not talking about electronics, I'm talking about tire compounds and suspension setups)
     
    #9 Tideland Prius, Nov 15, 2009
  10. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    17,557
    10,324
    90
    Location:
    Western Washington
    Vehicle:
    Other Hybrid
    Model:
    N/A
    I'm more worried about the mountain roads marked for 80 km/h (or the US equivalent), and some corners marked with advisories for 65-70 km/h, but with the gravitational potential for rolling at 150+ km/h. CC still works here, but I am too queezy to free roll.
     
    #10 fuzzy1, Nov 15, 2009
  11. Tideland Prius

    Tideland Prius Moderator of the North
    Staff Member

    Joined:
    Oct 2, 2004
    45,024
    16,242
    41
    Location:
    Canada
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    Ohhhhhh.... yeah ok in that case, I'd be worried too. There is the Sea-to-Sky that's 80km/h with 65km/h corners (I think it's 80km/h).
     
    #11 Tideland Prius, Nov 15, 2009
(You must log in or sign up to post here.)