What do we do for fun at the Cars.com offices? We take three $80,000- plus luxury convertibles and see which one rules for high-class summer cruising. The latest Cars.com faceoff features three of today’s top luxury droptops: the 2007 BMW 650i, 2007 Jaguar XK and 2007 Mercedes-Benz SL500. All three have power and looks, but we also took wind noise and ease of retracting the top into account — along with a number of other factors — to determine our winner.