Sperrdifferential

[the bruce]

"Volkswagen has been working with Haldex for a number of years to develop an
electronically controlled mechanical locking differential which Volkswagen refers
to as VAQ.
Similar in concept to the Haldex coupling used in Volkswagen's 4motion AWD models,
VAQ utilizes a multi plate coupler that electronically modulates power to either the left
or right front wheels as needed. This torque vectoring effect results in power going to
the wheel that needs it most. In dry situations, for example, at extreme cornering
attitude where the inside front wheel has lost traction, power is diverted to the outside
wheel instead (as long as the inside wheel is still slipping). Engineers that have driven
this system extensively say that you can literally feel the front end pulling itself around
the curve."