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2018 LT cruise control does not appear to control speed adequately

2420 Views 5 Replies 4 Participants Last post by  DrivenDaily
I have a 2018 LT, when setting the cruise control you expect it to be within an acceptable range and it does on flat surfaces. However even the slightest decline will cause a 5-10 MPH difference and it just doesnt seem right. No other car I have had does this (had an 07 LT and it worked great). There are many areas near me that are 30 MPH and I like to set it so I don't get a ticket. I can go anywhere from 28-45 on that stretch, which is counterproductive. I am not sure if this is because its a 4cylinder and my old was a V6 but it just is unreliable. Anyone else?
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My 2009 Malibu V6 also could not maintain speed properly on a decline. For whatever reason, GM stopped programming the transmission to downshift and use engine braking to slow the car.

I agree, it's frustrating and stupid. I use cruise control all the time and it was a significant flaw in the system to have the car speed up so much on every down-hill stretch.
I am not sure i follow the idea here. Is your car not slowing (ie if set to 45 and you go downhill it increases to 50+) or is it slowing to maintain the set cruise (if set at 45 stays 44-46)?

In my 2016 1.5T the cruise slows the car down using a lower gear when going downhill if the speed increases 2-3 mph above the set speed. If I set 45 it will maintain 44-46 mph up or down hill. Other users ( not me) have actually posted complaining about this as they would prefer the car roll downhill and not force slowdown. In the thread linked below, a 2019 owner complains about the car slowing to maintain speed when in cruise. My 2016 does the same. It would seem odd if not a malfunction if a 2018 was doing something different.

See this thread:
The CC on my 2011 V6 will not do anything to reduce the speed. It controls only the throttle. I've never driven a car that will slow when going too fast downhill.

In all of my cars, ever, I've either accepted the new speed and done nothing, or geared down manually.

I can understand that having to shift manually when you've got the car set to "fully automatic mode". If I were to drive one that slowed the car with the trans, I just might like it better as well.
I am not sure i follow the idea here. Is your car not slowing (ie if set to 45 and you go downhill it increases to 50+)
This exactly! So frustrating.
This exactly! So frustrating.
Why is it so frustrating?

In years past, Cruise Control simply operated the throttle for you, while you continued to do the rest of the job of driving. When you went downhill, whether you were operating the throttle or CC was doing it for you, the car still picked up speed and it was up to you, the operator of the vehicle, to decide if you wanted to let it drift or to slow down.

Do you expect the car to handle all of those chores for you? If so, maybe you need a different car. If your car is not designed to slow when CC is running the throttle, then accept the fact that YOU have a job to do and just do it. If you want a car that slows for you, find one that does and buy it.

CC is a convenience. I prefer having it help me run the throttle and I can deal with the overspeeds on hills.

I prefer one with fewer Nazis and Nannies. The one I have has too many, so my solution has been to gradually eliminate certain ones of them to bring the car to operate the way I want it to.
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