Ford’s new Mustang GT Shelby 500 is a 700-horsepower monster Ford says is the quickest street-legal Mustang in history. The latest iteration of Ford’s Shelby GT variant of the iconic Mustang pony car inherits the name of racer and engineer Carroll Shelby, who worked with Ford to design the first GT500 in 1967 — a car that now is considered a legend among American muscle cars. The new version, which debuted at the Detroit auto show on Monday, goes from 0 to 60 miles per hour in the “mid-3 second” range, Ford said. It borrows technology from Ford’s GT super...