The last Audi I owned was built before ACC was invented (B5 A4). That car was replaced (after 13 years of ownership it got totaled) with a Dodge. (I wanted something with 7 seats and feel a SUV wearing the badge of a highly engineered performance car company is sacrilegious.)

The Dodge has ACC, a feature I've come to love, and don't think I'd ever invest in a car that doesn't have it. In my Dodge, the ACC will bring the car to a complete stop if traffic ahead stops then start moving again when traffic moves. There isn't any upgrade above & beyond ACC necessary in order for that to happen, that's just how ACC works in Dodge vehicles. (By upgrade I mean, for example, Mercedes has "Distronic" and "Distronic Plus". A car equipped with the latter brings the car to a complete stop, the former does not.)

I assumed for years that ACC behaved the same as my Dodge in every car that had ACC. (Cruise Control behaves more or less the same across all manufacturers, as does the heater, AC, ABS, etc. Why wouldn't ACC?) I learned on the fly when driving a Toyota w/ACC that's not the case. When traffic ahead of me slowed enough, rather than continuing to slow and coming to a stop, Toyota ACC just disengages, so the car goes into a coast. If it doesn't actually speed up as a result, it sure feels like it does. (According to Toyota, in later models that doesn't happen, the system brings the car to a stop like the Dodge. I haven't driven any to confirm that.)

I've been shopping for a car for my mother. My criteria is small-ish wagon with AT, AWD, and ACC that isn't a Subaru. She liked the way my A4 drove so I thought A3 or A4 Avant. (Please don't suggest an AllRoad, they remind me too much of the AMC Eagle of the 80s.)

It seems Audi has (had?) two versions of ACC. ACC or ACC w/Active Braking Guard. The description I got from Audi is "braking guard is active at speeds above approximately 30 km/h and if the car in front of you is running slowly, but brakes abruptly, the safety system will activate at the point where impact can be lessened, or avoided all together."

I imagine as company representatives they aren't allowed to say "Yes, our system will bring the car to a stop." for liability reasons. So I'd like to hear from folks who've owned an Audi equipped with ACC... Does it bring the car to a complete stop when traffic ahead of you stops, or not? ... Also, their terminology "at speeds above approximately 30 km/h" implies that if traffic is moving too slowly then the feature won't function. (My Dodge has creeped along as slow as 6mph in rush hour traffic.) If the speed drops below 18mph what happens? Does the feature just disengage like I described the Toyota doing?

TLDR:
In an Audi...
Does Adaptive Cruise Control bring the car to a complete stop if traffic ahead stops?
Does Adaptive Cruise Control maintain speed & distance at very low speeds?
Does all Audi Adaptive Cruise Control behave this way or do I need to make sure the is equipped with Adaptive Cruise Control w/Active Braking Guard rather than simply Adaptive Cruise Control?