Audi has unveiled a new version of its quattro four-wheel drive system that it claims provides a critical improvement in efficiency.
The new quattro system uses an electro-mechanically operated multi-plate clutch and rear gear set that combine to eliminate mechanical drag by completely cutting drive to the rear differential, and with it the rear wheels, when the driver only requires front-wheel drive.
To be marketed under the name quattro ultra, the new system abandons the widely used Torsen torque sensing system, as well as the central differential and rear differential hardware used by Audi in one form or the other since the inception of its original quattro four-wheel drive system back in 1980.
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