It’s hardly more than a rumor now, though two reliable sources say it will happen and Aston Martin doesn’t categorically deny it. “It” is a new ultimate version of Aston’s well-liked DB9 grand touring coupe. Tentatively labeled DBX and whispered as a 2012 model, it should build on the recently introduced DBS to be the fastest, most powerful car yet seen from James Bond’s preferred motorcar purveyor. Would you believe a 700-horsepower twin-turbocharged V12? That’s the buzz.