Transverse quattro systems
In some recent quattro-equipped models using a transverse engine and transmission positioning (i.e., TT Coupe and Roadster, and A3), power is sent primarily to the front axle. As a result, quattro badged cars using this configuration cannot be said to have a "permanent" all-wheel drive system. A Haldex electrohydraulic center limited-slip "coupler" (i.e. not a differential in the true sense), may divert up to 50% of the power to the rear axle as conditions warrant. The power split between left and right wheels is achieved through limited slip differentials with electronic locking. This system is also available in A-platform Volkswagen, Seat, and Skoda vehicles, such as the Golf R32, under the name 4motion, on which the subjected Audi models are based. The exception among Volkswagen models would be the B5 Passat, which uses the aforementioned Torsen-based system.
vir:
http://en.wikipedia.org/wiki/Quattro_(a ... ive_system)