The trim, tech-savvy Audi A4 and its sporting S4 spin-off return for the 2014 model year with only a couple of minor changes. That's fine; in their niche, they're appealingly unlike the other Germans, totally distinct from the more brazen Cadillac ATS, too. The A4 is a bread-and-butter car for Audi, but it still draws a self-selecting...