In the superluxe world, we're used to this maneuver: add a few horsepower, shave a tenth or two, sew in a few extra threads, name your exclusive new interior color something like "Algerian Beet" and voil�, a 50-percent price premium for three-percent more car. On the surface, the Bentley Continental Supersports is a GTC Speed that has gone on The Biggest Loser, Extreme Makeover, and Alter Eco. But you know what they say about the proof and the pudding,...