DillonM

I hit a couple corners really hard for the first time and was just curios if the sport diff is something that you can actually hear/feel working. I assumed it was a behind the scenes thing and you wouldn't notice it much. It seemed like I could actually feel it, and want to say I heard something too. Off topic question -- what are the two clicks that you feel in the gas pedal once you reach 25 mph for the first time after the car sitting for a while?

xtreme571

I've done some aggressive turns and high speed on/off ramps, and I haven't heard the diff. On your off topic question, I had heard this was the ABS system or something. I want to know more about this.

Eli McCraig

I tested an S4 without the sport pack and an S5 Coupe with the sport pack last weekend. I could feel the difference, but only at ridiculous speeds around corners I shouldn't have been taking at ridiculous speeds. I could definitely 'feel' the car with the rear diff wrap itself around the turns. My perception was that I could 'hear' something going on in the *** end, but I was so blown away by how it felt as it did its job, I can't be sure. I slept on it for a week, going back and forth. And though I will rarely use its capabilities, I ordered an S4 with the sport pack. If at the very least it could be helpful for collision avoidance. And those red brake calipers...

superswiss

I never heard anything from the sport diff, but it can definitely be felt especially in Dynamic mode. You don't have to drive at the limit. You can feel it around town. Take a corner and get on the throttle at the apex or just before and observe how the car tightens the line. That's called throttle steering and is generally only associated with RWD drivetrains.

AndroidRobot

I don't have a S4, but my SQ5 had the sport diff. You definitely notice it in the corners because you don't have to steer as hard even at lower speeds. C&D did a test a while back showing that less steering was require when using a sport differential as seen in the article below. The Sport package offers more than the differential too so I would get it.

http://www.caranddriver.com/features/whats-the-diff-we-put-torque-vectoring-to-the-test-feature

Lastly here's a video Audi made showing how it works/benefits of the system

https://youtu.be/rQowh2Kr38s

markcincinnati

The S4's have brake based "torque management." I believe it is described (briefly) on page 146 of the owner's manual -- I'm saying this from memory, so if it is NOT on page 146, my apologies.

"Gear based" torque vectoring can't (as far as I know and have experience) be heard. The effect of its actions are noticeable ("felt") under circumstances that are toward the extreme. If you have passengers and attempt to "use" the TV (remember the meaning of "car-sickness"), you will really have to force the issue by approaching 9/10ths. It is interesting to note that one of the reasons the threshold to "feel" TV has gotten higher, is that the S4 employs "inside front -- and, when required, inside rear -- braking" under the guidance of the car's computer.

The RS3 relies exclusively on BBTV (brake based torque vectoring) to fight understeer (plus the RS3 offers larger footprint front tires over the rears). The S4 -- even without the sport differential -- works to improve the car's proclivity to understeer via brake based "torque management." The thing is, it is "interesting" to suggest torque can be managed via clamping the brakes which actually just subtract power rather than "re-route" it. It is hard to argue long and loud against it, however,since it works. It works so well it pushes the limits higher for the sport diff to "kick in" in any noticeable way (unless you regularly and frequently push the S4 "ludicrously hard" into corners). You may be able to prudently drive like this. If so -- I am jealous. My opinion is that the vast majority of the time "we" can't drive in such a fashion to actually appreciate the rear TV diff especially considering the yoeman's job done by the BBTV that comes as standard equipment.

On the other hand, the red calipers can be seen (and even though they used to be a $400 standalone option, the additional $2,100 for the red calipers isn't really THAT much of an inhibitor -- especially since you do get a $1,100 sport diff and apparently $1,000 of adjustable struts) and they look awesome.

Get the sport package if you think you can push an S4's BBTV beyond its limits on a regular (and frequent) basis. Or just get the package for the great looking calipers and hope that you'll push the car to the limits of its adhesion and understeer with some regularity.

The thing they bundled and called sport package is the only regret I have -- I love the look of the calipers and I love the IDEA of the TV sport diff. I'm rather indifferent about the adjustable struts.

One last thing, BOTH my sales rep and the service department all but said, "if you're planning on keeping the S4 out of the warranty period, consider either adding the cost of an extended warranty or trading the car in so that the sport diff becomes the NEXT person's problem." Contrary to what I thought they would say, they said the adjustable struts are virtually trouble free (and they are inexpensive to replace).

Food for thought.

Twowheelsgood

The S-Sport package comes with the sport diff that implements mechanical torque vectoring, which can be adjusted in different drive modes. In Dynamic mode you can easily feel it driving the outside rear wheel, giving the car more rotation than a nose-heavy AWD car would normally provide. In Comfort, the diff is dialed down and you can feel it though it's subtle. It feels a little artificial to me but it's effective and makes the S4 more fun even at near-legal speeds. It factored pretty high in my choice of the S4 over the C43 or BMW 340i xDrive. I once tested a BMW M235i xDrive, which in RWD form is a great car. But in AWD with an open diff and only brake torque vectoring, it felt much less composed than my old B8 or new B9 S4. I never had an unchaperoned test ride in the C43 so I didn't have a chance to see how well it corners.

If you think the diff is making noise, head straight to your mechanic!

mplsbrian

OP: it is possible to feel the sport diff working. The best way to demonstrate this on a test drive is to set all Drive Select individual settings to "Dynamic" except for Sport Diff (set that one to Comfort) and then take a corner under throttle while in 2nd gear (use the paddle shifters or put the transmission in manual to). Then, change the setting for Sport Diff from Comfort to Dynamic, go around the block, and do it again. You'll feel the rear kick out this time. And no, you don't need to be at 99% of the car's limit to feel it...don't let certain people on this forum who didn't spring for the option tell you otherwise.

You should never hear anything from the diff no matter the mode. If you do, something is very broken.

AndroidRobot

My thoughts exactly.

Comfort mode turns off the sport diff contrary to what others have said. You're the first one to get that part correct. People need to RTDM these days. The sport differential does make a big difference if you take any corner which is why I have mine set to dynamic in individual settings.

superswiss

Sorry, but that's very wrong. Comfort mode does not turn off the sport differential. It rather emphasizes vehicle stability over agility in comfort mode. In comfort mode, the sport diff is more about counteracting weight transfers and stabilizing the car in any situation. Here's a good write up from a while back. Still very relevant on the various systems that are controlled by Audi Drive Select. It goes into a little bit of detail on the sport differential and the different modes and how the various systems related together.

https://www.audiworld.com/articles/q...ism-redefined/