Yep, and as I said, particularly annoying that such is the case primarily because Audi wanted better fuel economy.

 

Has anyone ever see the video of the RS3 vs RS7 ? I work for Audi and after watching that video I think the RS3 is going to be a beast . But if it breaks everything going be over priced to get fixed lol

 

That's not really true. The current Haldex systems are electronically controlled, meaning the clutch can engage predictively based upon driver inputs/actions. It's not a purely reactive mechanical system anymore. The same sort of setup is employed in modern Torsen differentials, and TVD like in the RC-F. The C63 S has an electronic differential, while the C63 does not... the difference being the electronic one can "think" ahead to when it is needed, rather than being purely reactive.

 

What odd comments. Mechanical gear differential systems like Torsen aren't "reactive" - torque bias is implicit in the design, and the torque delivered is based on the available grip; there's nothing to "react" to, hence why Torsen-style differentials are often referred to as "torque-sensing". The Haldex system is referred to as reactive because by default, Haldex is full FWD, and then the decision to lock-up is electronically controlled. It is reactive precisely because, as you say, it engages only when the ECU is programmed to predict it.

Your attempted comparison to the AMG system used in the C63S/E63S/AMG GT also belies your understanding of how Haldex works, as AMG's system is essentially an electronically-controlled LSD as part of a greater chassis management system - i.e., like other similar concepts such as torque vectoring, the end goal of the additional layer of electronic interference is overall system management, not an improved reactivity of an LSD.

The latest Haldex (Gen V) has been particularly criticized because it dropped the traditional pump design in favor of a slower valve system, probably as a cost-cutting measure (although to be fair, that also cuts some weight). That's why gear differentials like Torsen are so favored by enthusiasts - even those in the Audi community are pretty critical of Haldex (go check any of our neighbor Audi forums if you don't believe).

Personally, the bigger fault with the Haldex is that it is by default FWD and can only send a maximum of 50% torque to the rear even when locked. Specifically to the RS3, lack of a front LSD also hurts cornering performance (even the MB A45 has a front LSD despite also using Haldex). But I suppose Audi has never been that serious about cornering in most of its vehicles.