The 2015 Audi S4 is an all-wheel-drive sports sedan that is the performance variant of the A4. Its sole powertrain ... and the optional sport rear differential. In a 2013 First Test we said ...

Both the front and rear end of the A4 are all ... and a new trick center differential on the S4. The A4 Avant (station wagon, in Audi-speak) is discontinued for 2013, though it does live on ...

Quattro with Ultra technology also is not compatible with Audi’s rear sports differential. 2017 Audi A4 Allroad Quattro: The Only Way We Get an A4 Avant Audi Switches Focus to eTron, Delays ...

It also can have Audi's sport differential, which is a torque vectoring rear diff that can send nearly 100 percent of the power to one wheel. Otherwise, this has the changes you'd expect that make ...