The BMW 3-Series has been the gold standard for small sports sedans since America had a gold standard. Well, it seems that way. The Ultimate Driving Machine has seen off the Germans (Mercedes C-Class, Audi A4), Americans (Cadillac CTS) and Japanese (Infiniti's G-force). Repeatedly. Despite the min-Merc's rep as a credible corner carver, it's the Infiniti that's posed the most dangerous threat to the 3's rep. In fact, Infiniti's persistence is the automotive equivalent of the posse in Butch Cassidy and the Sundance Kid. Who are zees guys? These days, the G-Unit chases the 3 with a bigger engine, remapped power delivery and a Bimmer baiting tagline: "Beyond Machine." We shall see . . .