Yeah like I said, not sure I believe them but that's what I was told. Then again, as Glisse or superswiss (who always seem to know a thing or ten about these sorts of technical topics) can probably tell us, not all DSG units are equal/identical across the models either. Maybe the torque-uprated A6/A67 unit that physically didn't fit in the B9 platform? No idea, just a guess.

I think Glisse pointed out somewhere in another thread that the A6/7 is equipped with Quattro Ultra rather than a torsen center diff, which most likely means that the DSG they are using was custom designed for that application. The DSG that is fitted to the A4/5 with it's torsen center is the one that could not handle the torque demands of the S4/5. Now I'm sure Audi could have spent boatloads of cash to redesign a DSG that could handle the torque needs of the B9 S models, and then used them across the entire B9 platform, but that probably didn't really make a lot of economic sense and would have likely bumped the MSRP up in a market segment that is still somewhat price conscious. Using the ZF for the lower production numbers of S models just makes more sense in that regard.

Also - I think the answer we keep hearing about the DSG not being able to handle the torque of the V6T is incomplete. I think the full answer is that it can not handle the torque "comfortably" at the lower RPM's that the V6T is capable of producing. It's as much about the driving comfort as it is about the actual physical engineering limits of the hardware.

Good thought. This makes a lot of sense, especially coupled with reports of people's previous-gen S4s being jerky at low speeds. There is also the matter of servicing intervals: the DSG flush/service on the B9 A4 costs several hundred bucks and is due every 40K miles. Even if adapted for a high-torque application like the S4, I imagine they'd need to reduce the service interval and that would drive TCO to borderline unattractive level, especially as engineers and executives give some side-eye to the shiny, smooth, torque-ready, lifetime-service ZF unit sitting on the table over there...

Audi already uses the ZF in several other cars so it makes sense to use it where ever they can to lower costs.

Absolutely that is the reason. They cannot mask the affect of high torque at lower rpm on such a direct drivetrains as a self-locking centre differential.

Audi received plenty of criticism in the past for the S tronic transmission not being smooth in traffic conditions, from both owners and the media. The USA market was particularly sensitive to this issue, probably due to the popularity of torque converter transmissions vs Europe where manual transmissions were more common. Both 8R Q5 and C7 A6/A7 models using the previous 3.0 TFSI supercharged engine were fitted with the ZF 8HP transmission in North America. Everywhere else in the world, they used the DL501 S tronic.

BMW's M Division have also said they will move away from dual sequential transmissions as well, for the same reasons.

Pity, but then again to get a dual sequential transmission to "behave" at lower speeds, they don't feel that much different to a good torque converter like the ZF 8HP. BTW, the version ZF supply to Audi is specifically made for a self-locking centre differential, and also Audi use at least 3 different versions of this transmission.

I just don't like the slight rubbery feel of a gear change in a torque converter vs the snick of a dual sequential. No matter how quickly the torque converter's clutch locks up. But no big deal in the scheme of things. The software mapping is much more important.

I was talking to a buddy of mine who just bought a 2018 BMW X3 with the same 8-speed ZF transmission and it claims to support launch control. It sounds like a very similar procedure to the non-LC Audi (ESC off, sport mode, brake and accelerator to the floor, go!), and I couldn't find any info about whether it's just a marketing tactic or has a meaningful effect. Does anyone know?

Here's a link with a video of the flag that pops up when it's "ready".

The ZF8 with sport enabled has launch control. I have no idea why everyone keeps claiming "it doesn't". My Audi does it, my BMW does it (both have the ZF8).

Here is a video for the Audi to engage:

You enable it, put your foot on the brake, pin the gas, RPM's hold at 3000RPM, and then you let off the gas. It still has a torque converter, so there is limitations on how it works (it won't rev above the torque converter full lock RPM), but it's still "launch control".

The catch22 is using LC is insanely hard on the torque converter as well as transmission fluid. With the DSC it could rev the engine higher and just engage the clutch (no torque converter to stall).

The ZF8 is a great tranny. Smooth, shifts fast, I have zero complaints.

Humble apologies. I missed the s-tronic comment in the manual. Is that something that can be coded in? My BMW 340i has the ZF8-45 transmission, and it does launch control as long as the sport transmission option (paddles, faster shifts) was purchased (or coded). Audi should be able to do the same (one would think).