Of all the Mercedes-Benz models that could be accused of being born with a silver spoon in its mouth, the SL arguably tops the list. Unlike many grand-touring cars, the Mercedes SL has never been forced to compromise its blue-blood personal-luxury/sport ideals with feigned attempts at practicality to please executives or attract buyers. It has, more or less, remained an unapologetic take-it-or-leave-it proposition since it debuted nearly six decades ago, and the 2013 SL550 does nothing to alter its course. Cool, Quiet Confidence Every move the 2013 SL550 makes is steeped in a competent, laid-back confidence; pin the throttle, and the car takes a moment to gather itself, as if saying to the driver, “Okay, dude, you ready? This is gonna be pretty awesome.” And with that, the seven-speed automatic downshifts, the twin turbos gorge themselves on air, and the whole shebang takes off, pulling hard to an observed 159-mph top speed (Mercedes claims an electronically limited 155). Life in th...