I'm really dissapointed in Audi....Acura has been offering this same concept for a couple of years now in their "Super Handling" modes and they are a primarliy a FWD manufacturer. Now they even offer it on their SUV's! If Audi's are the razor edge AWD manufacturer this should have been offered years ago with Audi. If Audi was holding something back for marketing purposes shame on them, if it was holding back because they didn't think of it then shame on them....but AWD for Hi-Po applications is their thing and just offering a 60/40 rear to front power bias in the RS 4 when Acura already had their "Super Handling" on the market is pure B.S....and Acura put it on their top end luxury model no less. If they claim that this is a high performance option, maybe Audi is not the manufacturing/design inovator that I believed that they were especially in light of the price premium on their products. We should have seen this differential/axle set up years ago on the 8 series models and it should have filtered down through the ranks into the A models by now. This should not be an optional item nor should the fact that it is a "new" option for them be anything that they should be proud of. I have never driven the Acura SH AWD but I hear that it is very very competent.....Not a good move Audi, you guys should have quietly introduced this as a design change and left it at that.

Probably because they don't.

A reactive system like the one used on the Hondas er um Acuras...is not the same as torsion. Nor can their ESP go beyond 80% without the ABS and throttle body going nuts. The cars do not compare, not matter how you try and work the angel.

at the wheels to overdrive the outside wheel. No Torsen diffy that I can see....

Eveen if they don't have a toresn either, which I am not sure of, their system works well and has worked for a few years. The way the article reads is like Adui just came up with ths new Sport diffy idea for the industry and that is not the case. They should have had it a few years back.

The Acura has a FWD bias and drives more like an FWD car, it's not nearly as sporting as the Audi.

Acura didn't invent the technology. It's from Ricardo.<ul><li><a href="http://wardsautoworld.com/ar/auto_grip_grin_2/">You can learn more about it here.</a></li></ul>

All A4s and above use Torsen, and it probably took time to develop the vectoring in the Torsen.

<center><img src="http://pictureposter.audiworld.com/70314/dsc006781.jpg"></center><p>
it is marketed as late as it has been. The A-8 flagship model should have seen this technology long before Acura's flagship car in light of the fact that Audi is the premire AWD manufacturer for performance cars. There should have been a trickle down to the other models long before this especially for the price and other technologies associated with their cars.

Quote from the atricle "How does it work? The center section of the differential is surprisingly no different than a traditional open unit. On each outboard side, there is "superimposed gear stage" meaning an overdriven gear capable of turning either of the rear wheels 10% faster than the input speed. Each side has an electronically controlled clutch pack which can engage the "overdrive" gear. The clutch engagement is variable meaning either side can be sped up at any interval between 0 and 10%. This speed differential can send nearly all of the rear axle torque to one side, as long as both wheels are getting traction. The engagement of the differential clutches is dictated by the same sensors which control ESP operation (wheel speed, steering angle, yaw, etc). The behavior of the system can be further altered by the ADS (Audi Drive Select) mode.

Don't get me wrong I like the car it is a hopped up A-5 with four doors. I guess, however that I am a B7 guy as I liked the sound, torque characteristics, the feel and the performance of the 40V in my 2005 S-4 Avant. I never bought it for mileage. With a Miltech exhaust, Stop Tech brakes, REVO flash, Nuespeed rear sway bar, custom pedals, Dolphin Grey with nappa silver seats, paddle shifters, BBS wheels and tinted windows the car was a hard package to beat for me. Performance, utility of a wagon and performance of an exotic...I'll have another if I don't do an S-5...so please excuse my rant but Audi should have had the sport rear differential first.
Cheers

powerslide, or drive the car at the very limit of traction.

To be honest, many S4 owners wouldn't benefit much from it.

It's for the kind of person who regularly turns of the ESP and likes to slide the car around a bit.

New Sport Differential should be standard on S and RS cars at the very least, and really it should have been in the lineup in some capacity years ago. I remember reading about the upcoming Torque Vectoring a couple of years ago and I think it should have been production ready and spec'd with the S5 at the start of it's run.

The verdict on the reviews that are out state that the Sport Differential is a must have. If Audi offered it as a retrofit, I'd be all over it. The reviews are highly positive about the difference the new Sport Differential makes on their test cars and I don't think Honda will have the same level of driving dynamics that Audi is getting praised for with this new setup. One thing to note is that Honda sales are falling like a rock and they are losing market share in the luxury segment very quickly. Acura is struggling severely. Contrast that to Audi who is gaining market share and in the US market is selling about the same as Infiniti now.

Take BMW's Active Steering for example. Yes, they were first to market with the concept of variable ratio steering, but the actual execution was far from optimal and has been generally panned by most critics.

Audi, while not first to market, used a much different engineering application (harmonic drive) for their variable ratio steering. It works much more effectively and has been praised to a greater extent.

I give props to Acura/Honda for SH-AWD. They are also a company of engineers and they are innovative. Remember 4WS on the Honda Prelude? It was a novel concept and worked well but unfortunately never caught on or took off. I worry about SH-AWD may suffer the same fate since decided to apply to their Buick-ish RL model first.

The real test will be seeing how it takes off in the new TL. This is admittedly a more sporty car so we'll see if people appreciate SH-AWD more in this application.

Audi may have waited to put the Sport Differential on the new S4 but the fact they intended it for a sporty application speaks volumes.

Combining the Sport Differential with Drive Select is brilliant in my opinion. Being able to vary the steering ratio, dampening, and torque split front to rear and side to side all at once is phenomenal. Early reviews have noted how it all works together seamlessly and transparently, really transforming the car.

I'm looking forward to reviews pitting the TL SH-AWD against the new S4. Guess that will put this thread to rest...

two Torsens all I need is more power to be able to drive my car with the tail out.

If you never driven an Audi with twin Torsens on snow, you've never really driven a Quattro. ;-)<ul><li><a href="http://books.google.com/books?id=DOu3ucfHxZcC&amp;pg=PA358&amp;lpg=PA358&amp;dq=torsen +differential+on+Audi+V8&amp;source=bl&amp;ots=2jeQ3V2iOQ&amp; sig=cnnC9wiZrgOuSPH6EXP-6MkkTz4&amp;hl=en&amp;sa=X&amp;oi=book_result&amp;resnum=4&am

<ul><li><a href="http://www.torsen.com/files/Torsen%20Application%20Chart.pdf">Torsen US Application Chart</a></li></ul>

I think the sport diff will help ANY car in the Audi lineup. However, I think Audi made the right move in rolling it out in the S4. I think the typical S4 driver will appreciate this feature more, not to mention it's better suited for the chassis dynamics of the smaller car.

be a S4 DSG with sport diff.

I'd get the manual tranny if I could, but since the car is paid for by the company, it has to be a clutch less car.

Still considering putting a twin turbo 4.2L V8 in the old V8. The conversion would make better than 500 Hp. That would be fun!

Quattro than a Torsen center differential...

<ul><li><a href="http://corporate.honda.com/press/article.aspx?id=4096">Torsen != AWD</a></li></ul>

<ul><li><a href="http://forums.audiworld.com/s4b8/msgs/1080.phtml">http://forums.audiworld.com/s4b8/msgs/1080.phtml</a</li></ul>