Launched in 1999, the venerable 6.0-liter V-12 has served Aston Martin well for the past decade and a half. Its roots are in the Ford 3.0-liter Duratec V-6 of that era and, apart from marketing purposes, it’s really a 5.9-liter 60-degree V-12, displacing 5935 cc. Over the years, the engineers in Gaydon managed to turn it into one of the more exciting engines on the market, with sharp throttle response, strong high-end performance, and a stirring soundtrack. The downside: It’s a gas guzzler by modern standards, so change needed to happen. Revealing the replacement engine at the International Vienna Motor Symposium in late April, Aston’s chief engineer Brian Fitzsimons put it this way: “Further evolution of the current V12 as a naturally aspirated engine was not an option due to the environmental and legislative landscape that existed and was continuing to evolve.” The solution" Downsizing and turbocharging. The new engine is a 5.2-liter, 60-degree V-12; it is more oversquare with a 89.0 mm bore (same as before) and 69.7 mm stroke (reduced from 79.5 mm). Aston added two twin-scroll turbochargers, one for each cylinder bank, retained port fuel injection (saying that makes emissions treatment easier than with direct injection), and added a cylinder deactivation function, which can shut down an entire cylinder bank to reduce fuel consumption. The engineers adopted a system that keeps the valves operating normally on the deactivated six cylinder...