S4 8-speed question
 

It's an 8 speed ZF sport automatic. It is the exact same transmission as the newest SQ5. (I can't say whether the newest SQ5 has the same transmission as the 2015 you're familiar with, though.)

It does not shift as fast as the DSG but it is very, very fast, and much smoother to boot.

Just traded my 2017 A4 for 2018 S4; still early into break-in period, but am very pleased with the 8 speed, certainly nothing like the sluggish, imprecise feeling of the A4. Also have DSG on my S3, and the S4 transmission is every bit as smooth and precise; use paddles and I doubt there is a millisecond difference in speed.
I too had concerns about buying with the new 8 speed...bottom line, don't even think about it;....the S4 is a supercar in overall value relative to everything else on the market.

It might be easier to ask which car doesn't use a variant of the ZF 8HP: https://en.wikipedia.org/wiki/ZF_8HP_transmission This may or may not be fully up to date, I am pretty sure we have a "2nd generation" , HP55? It is a great transmission giving wonderful gas mileage when cruising in 8th and very responsive in "S" mode. I just read somewhere if you hold the left paddle down for a second or two it will downshift to the lowest possible gear and take the F off.... :-)

I'm very pleased with the sport tuned ZF8 speed transmission in the B9 S4. Crisp shifts yet smooth in normal driving.

-Shifts in 200 milliseconds
-Ability to shift in a non-sequential manner - going from gear 8 to gear 2 in extreme situations
-Quad planetary gear set design with dual simultaneous engagements

It basically behaves like a dual clutch but minus the jerky low speed behaviors.

Sadly there is no launch control with the 8 speed auto.....something the DSG was masterful at. Yes, that's not a daily use thing, but man I would miss no launch control.

Do you really think on downshifts from 8 to 3 gear when you floor it really are as fast as the DSG? I can't see how it can skipshift 5 gears as smoothly as the DSG and manages the seamless rev-matching of the DSG. I have yet to drive the new S-cars, but I'm ever-so skeptical it can perform like the DSG in very specific high-demand scenarios. Owners...am I wrong?

As you say, launch control is not a daily use type thing, but the same results can be produced using a manual launch technique. I've timed out a reproducible 4.2 seconds 0-60 using the launch technique. But I prefer not to do this very often (plan to keep the car ~10 years).

I too was skeptical of a non-DSG transmission, but after several months use I greatly prefer this over any DSG/DCT. This is not an ordinary transmission, it is upper tier stuff, with similar ZF transmissions placed in some RS models. It has lightning quick shifts (not as fast as DSG, but almost imperceptably close), but doesn't suffer all the herky jerky low speed stuff that plagues DSGs, or unpredicted gear hunting. The smoothness is a major plus. It also doesn't present an expensive ticking time bomb for owners planning on keeping the car past warranty.

Lastly, info straight from the manufacturer, ZF Friedrichshafen: "One of its main aims is to improve vehicle fuel economy, and it can achieve an 11% saving compared to the ZF 6-speed transmission and 14% versus modern 5-speed transmissions. Due to changes in internal design, the shift times have reduced to 200 milliseconds; additionally, the unit brings the ability to shift in a non-sequential manner - going from gear 8 to gear 2 in extreme situations." (Just noticed this was stated in an earlier post, but this is the actual paragraph)

All I gotta say is try it out yourself, but do yourself a favor and ensure it is in the proper mode: Sport and Dynamic. "D" mode is used to pass emissions regulations and uses very low performance mapping (most of us can't stand it).

After some 53,000 miles with the DSG in my 2014 S4, I was somewhat (not a lot) concerned that the 8-speed tiptronic would not be as smooth as the DSG. In order to make the point, let me ask that we imagine the transmission "scale" as having 1-100 gradations (with 100 being the best). My experience with the 7-spd DSG would lead me to grade it as a 97 (leaving room for something better to come along). By comparison, I would grade the 8-spd as almost imperceptibly different at a grade of 95. I was loaned a Q5 for several days recently, and, as you know, it has the 7-spd. I could tell the difference, but just barely. Given the choice, I'd still prefer the DSG, but the very slight differences that can be felt in the tiptronic are not off-putting. The issue, at this point, that I have is that the new A6 and A7 (with virtually the same torque as our S4's) will be equipped with the DSGs. I had read that the reason the S4 didn't get the DSG was that it couldn't take the torque of our turbo V6s. Perhaps the DSG is now "heartier" -- my guess, however, is that the B9.5 S4, like the RS4 and RS5, will still be equipped with the 8-spd given that the torque will tend to creep up.

There aren't enough "o's" in smoooth to describe my experience with the DSG in that car. . .

This should give you an idea of how it shifts. With that said, I think the DSG in my A3 was smoother. For me, the 8 speed hasn't been that smooth from 1-2 and 2-3 in some conditions (mostly cold but that's all it's been since I got the car) and while downshifts are good, the DSG definitely seems quicker. I would also love to know how it would perform with a DSG. In the video, it takes 0.5 seconds for the speedo to change from 57 to 62 MPH (right when the 2-3 shift happens). Now, of course, there might be some delay in the speedo, but I would like to see if the result would be different with a DSG.

I thought the DSG was a great transmission. Quick shifts with very direct engagement. Great for performance driving and perfectly acceptable for most of the daily commute. But where it really had problems was trying to guess the next gear in slow traffic, or when coming to a stop. The DSG was sequential and the dual clutches supported alternating gears so it was happiest when it could properly guess a 1 gear change up or down. When it needed to shift 2 gears however it had problems and the lag was perceptible. Even worse is when it guessed the next gear was down when it should have been up or vice versa. Then it was like riding the mechanical bull at Gilleys.

The ZF isn't quite as good when performance driving (but only by the narrowest of margins) and I attribute this to the lack of directness caused by the torque converter. But is far better on the daily commute and has none of the low speed bucking issues of the DSG.

In a perfect world we would have a transmission that combined the best of both world. If I had the option of picking either one knowing what I know now, I'd stick with the ZF.