Our waiting Infiniti IPL G Coupe idles curbside. Exiting its enormous Thermos-sized chrome exhaust tips, the invisible waveforms invite a closer listen. The baritone note suggests power, with a cadence that is is lumpy, sounding closer to a V8 with a heavy cam than any V6 we've ever heard. A harbinger of things to come, or just an evil audible tease? We had flown to California's Napa Valley to find out, but first we needed some context.