I needed a suitable car for a spirited 500-mile run to the “coolest small town in America,” and back. One leaped to mind: the Audi S4 with its optional active differential. In our first encounter, the current “B8” S4 underwhelmed me. Though quick and capable, it just didn’t feel special. “A4 3.0T” seemed more apt. But that car lacked the trick diff. And metro Detroit’s roads aren’t the most challenging. A re-test was warranted. The roads of Southeastern Ohio and West Virginia would provide it.