TESTED 2009 Mercedes-Benz SL63 AMG WHAT IS IT? Mercedes and AMG have taken the V-8 version of the SL luxury sports car in a more aggressive direction. HOW MUCH? $138,475 including the $2,600 gas guzzler tax, which is a third more than the basic SL550 ($99,375) or about half the price of an SL65 AMG Black Series ($299,000). WHAT MAKES IT RUN? 6.2-liter V-8; 7-speed automatic transmission with manual shift mode. IS IT THIRSTY? The E.P.A. thinks so, rating its consumption at 12 m.p.g. in town and 19 on the highway. THERE is good news for anyone who has $135,000 to spend on a sporty luxury car. First of all, you’re rich, so congratulations on that. Second, it’s hard to find a bad car for $135,000. Perhaps your tastes run toward an Aston Martin V8 Vantage, … Read entire article »