Soonermagic

VM - I like it. Makes perfect sense. Thank you.

Anyone have thoughts on #2 & #3?

chemengin

#2 - there is no specific speed that the car will apply emergency braking. Pre sense is active regardless if adaptive cruise is on or off. If using adaptive cruise, and the car detects an impending front collision, it will automatically turn off adaptive cruise and activate pre sense as usual

Soonermagic

Thank you chemengin. So I am a little confused and will try to illustrate my confusion. Let's say that I am at highway speed, using adaptive cruise control (ACC). My car speeds up and slows down based upon the speed limit that I set as well as the speed of the car in front of me. If I disengage the ACC, frequently I will then immediately see the blinking red "You are following too close" symbol. That confuses me as I expected the ACC to have been managing my following distance and thus, would only receive the blinking red symbol if I had shortened the following distance after turning off ACC.

chemengin

If I recall correctly, what you are referring to has nothing to do with ACC. You are referring to the distance warning that indicates when you are approaching a certain distance to the car in front of you. This is independent of ACC and pre-sense, and doesn't do anything other than visually inform you of your distance to the car in front.

Soonermagic

That is my understanding as well. My expectation is that the ACC is managing the following distance to ensure adequate time to stop. But that seems to be contradicted by the distance warning. In other words, if the ACC is hypothetically keeping me at a following distance of 50ft (based on speed, other cars) and then I disengage the ACC (while still maintaining the 50 ft), I wouldn't expect the visual alert. It leaves me with the impression that the ACC following distance was then not adequate. I do realize that I can change the following distance in ACC as well as the time for the visual alert. I guess I would expect these to be in sync with each other. Am I overlooking something?

chemengin

Honestly I don't know anyone that uses the visual warning. I would suggest just turning it off.

VM

I've noticed the same behaviour on my car, and I think here is the explanation: ACC has faster reaction time than a human, so when ACC is off, the visual alert system adds the 'human response' factor into the recommended following distance and therefore it goes up.

(Now, of course, I currently have a car with none of those features... and I miss them...)

Soonermagic

Thx VM. That makes sense.

borifly

Any way to retrofit the ACC? What would I need? I believe my Premium Plus has the bottom sensors already so it would be a matter of replacing the windshield and the camera?

SchwarzS6

Your premium plus has the camera but not the sensors. You may see 4 sensors in the front bumper but they are not used for ACC. The Prestige also has two radar sensors which are used for ACC. My guess is that in addition to not having the sensors, the car also does not have the wiring harness and it is probably missing a switch on the cruise control stalk. I could be wrong but I would guess more than $2k to retrofit if it is even possible.