I've had a 2018 Honda Accord EX, and now a 2020 Honda Accord EX. Both have "adaptive cruise control with low-speed follow". So with low-speed follow it's pretty clear that the computer, under cruise control, can control the brakes (you can feel it as well as see it when driving).

So: How come when going down a slope (not a hill, just a slope, probably <3%, or even <2%) the car will sometimes speed up far past the set speed, with ACC active?

The annoying part is sometimes. Actually it is most of the time that it speeds up far past the limit. Sometimes it holds to about 3-5mph past the limit. And I'm talking about the same slope - a road near my house I drive daily.

Should these Honda Accords be braking? Or should they not be braking? (I'd prefer braking, but would accept not braking. Sometimes braking seems braking. I mean, breaking. I mean, broken.)

  • Does the owner's manual describe the operation of the Adaptive Cruise Control? Jun 17, 2021 at 18:05
  • @DavidSupportsMonica - only how to turn it on (and off), and what it does in the most general way ("slows down the car if it detects a car ahead of you")
    – davidbak
    Jun 17, 2021 at 19:55

1 Answer 1


I've only test driven cars with this feature. But I would think that the vehicle would be designed to not brake automatically because the last thing I would want a car to do is to unexpectedly brake while I'm traveling down a hill covered with ice.

  • 1
    yes - although, these cars also have advanced traction control ... - and you shouldn't have cruise control on in an icy situation anyway, right? (or maybe you should with today's engine computers ... I don't know ...)
    – davidbak
    Jan 18, 2021 at 5:45
  • Yes, you are absolutely right. You don't use cruise control of any kind on slippery roads. That was my oversight. I would edit my answer, but the only way to correct it would be to withdraw it.
    – Jupiter
    Jan 18, 2021 at 9:59
  • My 2018 Toyota downshifts rather than brakes to control excess speed going downhill, as have several varied rentals I've driven. My last Honda 20 years ago did not have adaptive cruise...
    – Jon Custer
    Jan 21, 2021 at 18:17
  • @JonCuster - Ahh, I wonder if it is a downshift that should happen but its inhibited in some way - like not being in the right speed "band" to make it safe for the engine or maybe it's because I have "sport mode" on?
    – davidbak
    Feb 6 at 0:23

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