The model responsible for the pony-car craze, the Ford Mustang, is an American icon that has always stayed true to its roots of big power in a readily accessible package. Ford has come up with many limited-edition variants over the years, each ostensibly special in its own way, but there has never been anything like the new Mustang GTD. At first glance, its familiar shape might have you believe that this is just another marketing-led iteration that simply offers a big motor and an ever-bigger wing. That, though, would be a gross misestimation of a car that is a complete sub-surface reinvention in the Blue Oval’s pursuit of the ultimate track horse. With Formula 1-style active aerodynamics, a bespoke suspension, and a supercharged 5.2-liter V-8 that delivers 815 hp and 664 ft lbs of torque, the GTD is a blunt-edged, nose-heavy, big-fendered machine that sets new benchmarks for the model...