snagitseven

Most everyone is correct. To further clarify:

ACC will only track a followed moving vehicle in your lane, will maintain the preset distance range/speed and braking guard will stop your car if the tracked vehicle comes to a complete stop.

If ACC is not actively tracking or loses tracking a moving vehicle, i.e. a curve or hill, it will not track or stop if encountering a stopped vehicle (or any other stationary object for that matter).

There is no "training" or GPS involved with ACC.

irenesbob

That is precisely the problem with it and why I said it needed some way to “learn” driving routes. It should learn, as we do, “memory tells me there’s a hill a half a mile ahead” (not that I think machines talk to themselves) and then maybe get its foot over the brake pedal, so to speak, in case there are cars stopped over the hill. I think it is unwise to rely on machines to take actions when their ability to know or perceive variables that should be factored into their actions is worse than our own.
I have no problem relying on machines to do things like maintain a set speed, meter fuel to the engine, etc., but these are sort of linear operations that do not require any input beyond the vehicle’s design capabilities. Relying on ACC to keep you from hitting cars, cows, felled trees and people seems imprudent to me. Anyway, I don’t personally care for ACC at its current state of development.

Silent Drone

This. Mine came with a pamphlet on ACC that said this explicitly. I won't try to second guess why it operates this way, but the point is that this is part normal operation for the system.

DeerHunter

I think you and Audi engineers are on the same wavelength. The machine (ACC, in this case), is designed to do one very simple task: Keep a set distance from the moving object in the same lane as you - stopping if necessary and then restarting if said object starts moving within a few seconds. That's it - everything else is up to the driver, which is a much more complicated machine and capable of far more cognition. It assumes that you will notice the blind crest or stopped object in the roadway and take the appropriate measures to, you know, actually drive your 4,000 lb+ piece of very complicated machinery.

irenesbob

Not to beat this issue to post-death, but:
A friend of mine in Chicago told me that he hates the automatic braking in his new Mercedes.
His issue is that in stop and go traffic his style is to monitor the road several cars ahead of him and even if the car ahead is getting close he can see that cars two, three, etc. ahead are starting to move forward, so he can continue ahead cautiously with foot over brake pedal and continue to roll along without braking and without hitting anything. He does this to make the brakes last longer and use less fuel.
He has found that several times in this situation the MB’s auto braking function (whatever it is called) slams on the brakes and he gets tossed around a bit. I don’t have ACC so I cannot say whether it acts in a similar way, but what he describes sounds annoying, if not dangerous. It basically doesn't allow a good driver to keep their eyes open and proceed with caution based on seeing a long way down the road and being ready to brake if necessary.

irenesbob

Well said. However, from this thread I got the impression folks were expecting more from it.

Helmar

I stand corrected.

After the replies, I went out and made several tests and concluded that the above statement is indeed how it works. If it never "Saw" the object moving, it won't notice it.

Thanks for all of the replies.

HBH

snagitseven

Or if ACC lost tracking "lock" with a stopped previously followed vehicle as in your OP hill example.

qqq1970

+1. ACC can track a moving object that slows to stop, but not a stationary object. I believe it is in the manual.

dicktahoe

So here's a little summary of why I like ACC over a conventional Cruise Control. With a conventional CC, I have to be continually pressing the decrease speed button and then the increase speed button as traffic speed changes--the ACC does that automatically. If I want to look at or search using the MMI, I can spend a few extra seconds when using the ACC. That is I can relax somewhat and know I won't run into the car ahead.

Even if I'm not using the ACC, I still have Braking Assistance, so if I get too close to the car in front, I get "Red Cars" showing on my HUD, and/or if the car in front stops suddenly I get help to keep from rear-ending that car. And Yes, I do pay attention while driving, but sometimes things happen quickly and I appreciate the braking assistance, rather than my wife having to brace herself and yell, "Watch Out!".