2015 Prius v Adaptive cruise control annoyances

Discussion in 'Prius v Main Forum' started by Garry Thorpe, Apr 12, 2018.

  1. Garry Thorpe

    Garry Thorpe New Member

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    2015 Prius v wagon
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    i-Tech
    We love our Prius v, sing its praises. But there is one area that has not lived up to my expectations, the adaptive cruise control operation. Are my experiences common to other people out there? As a software engineer I feel these could easily be fixed in firmware, Toyota are you listening?
    1) Cruise surges over hills, getting up to 20KM+ over the set speed. 30 years ago my early cruise controls did this, but in all recent cars this has been all but eliminated. Example: I recently got a speeding fine with cruise set at the correct speed limit, wasn't happy!
    2) Adaptive cruise control "hunts" between accelerating and decelerating in certain conditions. At various speeds and inclines, the car switches between accelerating and regenerative charging about every second. This creates a mildly annoying jerkiness and can't be good for fuel economy and wear and tear. In some situations the motor is turned on and off frequently (every few seconds?). (Needs better hysteresis build in to the software).
    3) Adaptive cruise control overreacts to a car pulling in front of you. Even if a car is going faster than you, if they pull into your lane within the adaptive cruise control range, the Prius will aggressively brake, whereas as a driver I would do nothing and let the car pull ahead. I believe the software could be programmed to be more intelligent, it can quickly determine the relative speed of the new vehicle and if the distance is increasing, by all means ease off the accelerator, but don't brake. Example: on a moderately busy dual lane highway this created a near accident when someone pulled in front of the Prius. It suddenly braked hard and surprised the queue of drivers behind me who had to brake even harder.
    3) Adaptive cruise control overreacts to a car pulling into a different lane leaving space in front. In a queue of traffic travelling below the speed limit, if the car in front changes lanes, the Prius will aggressively accelerate only to have to aggressively decelerate at the next car. When the next car is still within the visible range of the sensors and is doing the same speed as you, please program the adaptive cruise to accelerate gently to close the gap, not charge up and brake hard. Teach it to take a "chill pill".

    Overall I find the adaptive cruise control is only effective in about half the situations I had expected to use it. It was my main motivation to purchase the optioned up model. What I would really like is a software update to address these issues. Surely this must be annoying to many other users...

    P.S. That begs the question, have there been any updates to address these issues? I couldn't find anywhere that lists software releases and what fixes/changes are included.
     
    #1 Garry Thorpe, Apr 12, 2018
    Last edited: Apr 12, 2018
  2. Air_Boss

    Air_Boss Senior Member

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    The standard Cruise Control works like a charm, no matter which driving mode is selected (ECON, NORMAL, or POWER).

    If the behaviors you describe are typical of Prius v with ACC, I'm McLoving it that the v Five without ATP doesn't have ACC.

    The only post-manufacturing firmware update I am aware of on the v was the IPM update, circa 2015.
     
    #2 Air_Boss, Apr 13, 2018
    Last edited: Apr 13, 2018
  3. taxibuddy

    taxibuddy Junior Member

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    Other can correct me if I'm wrong but I can't remember an instance of Toyota providing firmware updates simply to make improvements to cars already sold and on the road. I think they would only do it if they felt there was a safety problem. I suspect that to reflash most of the ECUs would require physical access to them and often partial disassembly of the car. For example, access to the ECUs behind the glove box requires partial disassembly.

    The big automakers consider themselves to be in the manufacturing business and manufacturing considerations dominate their thinking. A high level engineer in GM's research group told me that in relation to a research project I was working on with them. If you look at it with through the manufacturing lens, it makes more sense. Once the car is built, they are done with it. At least they hope they are. They want to concentrate their efforts on the next model.

    If you have any luck, let me know because I have a few obvious improvements to the display audio system.
     
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  4. mikefocke

    mikefocke Prius v Three 2012, Avalon 2011

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    Take a video and then supply it to a dealer. Are you under warranty? No idea what the warranty is in AU.
     
  5. fotomoto

    fotomoto Senior Member

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    Some of these issues are similar to the behavior of our Subaru Outback with eyesight. Think of these as simply version 1.x that are somewhat crude and simple in both design and operation.
     
  6. Offline

    Offline Active Member

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    Five
    Maybe the Australian version of DRCC is programmed a little differently. I've found that auto-braking under DRCC on both our 2012 Prius v and 2014 Sienna (it's a van a bit larger than the Australian Tarago) is harshest in several of the OP's scenarios when the following distance is set to the shortest of the three intervals. On a downhill stretch, our Prius usually auto-brakes well enough to not creep too much above the speed limit unless the hill is exceptionally steep. Our Sienna's DRCC doesn't auto-brake so I have to use the brakes on a downhill and then use the resume function.

    When a vehicle pulls in front of our vehicles such as when doing a lane change, auto-braking can be fairly harsh unless the vehicle is accelerating away at a higher speed. In this case, auto-braking and then acceleration can be substantially harsher on our Prius than on our Sienna. My assumption has been that the tolerances on the Prius are set at a higher sensitivity due to its much less powerful engine.

    DRCC doesn't turn a vehicle into a semi-autonomous vehicle. I find myself frequently cancelling and resuming DRCC as conditions warrant and more so when DRCC is set at the closest following interval. I've found that DRCC generally works more smoothly when set to the longest following interval although I frequently (sometimes constantly) toggle through the three following distance intervals when conditions warrant.
     
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