What? Hedge-fund managers, heads of surgery, corporate lawyers and their well-heeled, buttoned-up ilk don't need plug-in hybrids too? Mercedes-Benz is keeping such an audience in mind for its latest concept car, the Vision S 500 plug-in hybrid. Similar to the S 400 hybrid currently in production, the S 500 can also travel 18.6 miles in electric-only mode and take a battery recharge by way of an electrical outlet. What ever happened to greed is good?