quattro generation IV

Starting from 1995 on Audi A4 / S4 / RS4 (B5 platform), Audi A6 / S6 / allroad / RS6, Audi A8 / S8 with both manual and automatic transmissions. Also on VW Passat B5, where it was initially referred to as syncro, but by the time it reached US soil, it had been re-christened 4motion. Also used on the Volkswagen Phaeton and Volkswagen Group D platform sister vehicles. The Volkswagen Touareg used 4Xmotion with a separate transmission, PTUs and front axles.
The manually locking rear differential from the earlier generations was replaced with a conventional open differential, with "Electronic Differential Lock" (EDL) (which detects wheelspin via ABS road wheel speed sensors, and applies brakes to the one spinning wheel, thus transferring torque via open differential to the opposite wheel which has more traction). EDL works at speeds up to 80 km/h (50 mph) on all quattro models (on non-quattro models: up to 40 km/h (25 mph).
System type: Permanent four-wheel drive.
Torsen type 1 centre differential, 50:50 'default' split, automatically apportioning up to 75% of torque transfer to either front or rear axle.
Open rear differential, Electronic Differential Lock (EDL).[4]
Open front differential, Electronic Differential Lock (EDL).[4]


quattro generation V

Starting with the B7 Audi RS4 and the manual transmission version of the 2006 B7 Audi S4. It was adopted in the entire S4 lineup in 2007.[1] and become the standard fitment on all quattro Audis with longitudinal engine layout until replaced in the 2010 RS5.
System type: Permanent asymmetric four-wheel drive.
Torsen type 3 (Type "C") centre differential, 40:60 'default' split front-rear, automatically apportioning up to 80% of the torque to one axle using a 4:1 high-biased center differential. With the aid of ESP, up to 100% of the torque can be transferred to one axle.
Open rear differential, Electronic Differential Lock (EDL).[4]
Open front differential, Electronic Differential Lock (EDL).[4]


Vectoring quattro system

Audi's new sport differential, debuted 'torque vectoring' to quattro generation V. The Audi sport differential allowed the dynamic allocation of torque across the rear axle of the debut vehicle: the B8 (2008) S4, and is now an optional addition to all quattro vehicles, which continue to use the 40:60 asymmetric Torsen (Type "C") centre differential. The sport differential replaces the normal open rear differential while the front axle still rely on an open differential with EDL.[4]
The torque vectoring rear axle differential is designed & manufactured by Audi and is being offered on Audi A4, A5, A6 and their derivatives (including “RS” models). The "Sport Differential" selectively distributes torque to the rear axle wheels thereby generating a yaw moment, which improves handling and also stabilizes the vehicle when it oversteers or understeers, thereby increasing safety.
The sport differential operates by using two superposition ("step up") gears at the differential, which are operated via multi-plate clutches each side of the differential crown wheel. When required by the software (using lateral and longitudinal yaw sensors, the ABS wheel sensors, and a steering wheel sensor), the control software (located in a control unit close to the rear differential), actuates the relevant clutch pack. This has the effect of taking the output shaft drive through the step-up gear to the attached wheel, while the other shaft continues to drive its wheel directly (i.e. the clutch pack not actuated). The higher speed output shaft produces increased torque to the wheel, producing a yaw (turning) moment. In normal operation increased torque is delivered to the wheel on the outside of the turn thereby increasing the vehicles turning moment, in other words, its willingness to turn in the direction pointed by the steering wheel

quattro generation VI

Audi debuted the 6th generation of quattro in the 2010 RS5. The key change in generation VI is the replacement of the Torsen Type "C" centre differential with an Audi-developed "Crown Gear" differential. With the new "Crown Gear" center differential, up to 70% of the torque can be applied to the front wheels while up to 85% can be applied to the rear wheels if necessary. The net result of this advance in quattro is the ability of the vehicle electronics to fully manage the vehicle dynamics in all traction situations, whether in cornering, acceleration or braking or in any combination of these