Reflecting wider trends in the US auto market, Mustang’s third major redesign saw the width, length and weight increased substantially, all very evident in the new 1971 Mustang SportsRoof model with its nearly flat roof line. 302 and 351 engines, as did the Mach 1 and Cobra Jet models. Not long after launch, global fuel concerns started to influence sales and performance options; model offerings and horsepower ratings were progressively watered down through 1973.