I find Adaptive Cruise not useful in stop and go traffic. It takes too long and is drawn out when coming to a full stop, and it is too slow to start moving and follow the car ahead when leaving from a full stop.
Perhaps newer cars don't have this issue? <shrug> '14 RS7

Did your window sticker say it had the following options:
- Adaptive Cruise with Stop & Go
- Audi Pre Sense Plus

if not then we are not comparing apples to apples. The engine may not have changed much since 2013/2014 but the electronics have changed considerably

FWIW, yes it does.

Not specifically for the S6 and not like I couldn't live without it, but ACC is something that I wouldn't wanna miss on my next daily. My current car ('13 RS5) doesn't have Stop & Go, but nonetheless, ACC is one of my favorite features on long road trips and when the traffic flow is less than optimal. It's something I wanted, but I'm even surprised about how often I use it now. I do not drive in traffic all that much and I don't commute, but it made road trips a lot less fatiguing and when I do find myself in traffic it's a boon to keep me sane. It has become a deciding factor in future car purchases for cars I actually drive frequently. In fact I'm buying a '19 C63S for my next daily, picking it up in Germany in about 3.5 weeks, and I chose it partly over an M4 due to the lack of at least ACC in the M4. The C63S not only has ACC, but the driving assist features are at the level of Tesla Autopilot, so it can drive itself not only in stop&go traffic, but also at normal highway speeds. Even in a performance car, there are times when the driving is mundane, so being able to kick back a bit and let the car do some of the driving is rather nice. For those who find the system slow to respond, try adjusting it via Drive Select and change the distance to a lower setting. In Comfort mode it's very relaxed and in Dynamic it's more responsive and with a lower distance settings it follows the car in front faster. I've coded the default distance setting in my RS5 to 1. The factory default setting of 3 doesn't work very well around here. Leaves too much of a gap.

Thanks. This is helpful.

Ah ok - wasn't aware Audi updated the technology in the newer MYs, I have a 2013.